Atmospheric deposition, CO2, and change in the land carbon sink.

Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly contribute to changing carbon fluxes during the studied period. Our findings support the hypothesis of a general CO2-fertilization effect on vegetation growth and suggest that, so far unknown, sulphur deposition plays a significant role in the carbon balance of forests in industrialized regions. Our results show the need to include the effects of changing atmospheric composition, beyond CO2, to assess future dynamics of carbon-climate feedbacks not currently considered in earth system/climate modelling.

Montane ecosystem productivity responds more to global circulation patterns than climatic trends.

Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies.

[Experience with remifentanil in the ICU]. / Esperienza con remifentanil in Terapia Intensiva.

BACKGROUND: Analgesia and sedation are indispensable in patients admitted to intensive care for the following, principal reasons: to control their state of anxiety, induce amnesia, improve their adaptation to mechanical ventilation, make invasive manoeuvres tolerable. The purpose of the present retrospective analysis is to assess the effectiveness of remifentanil in a total of 1085 patients admitted to our Resuscitation and Intensive Care Department in 1997-2001. METHODS: A sample of 60 adults was taken from these patients. The group was homogeneous in terms of age (67.3+/-10.2 kg), weight (66.7+/-10.2 kg), duration of sedation (6.8+/-1.6 days) and index of gravity (SAPS 30.1+/-4.4). The patients were suffering from chronic obstructive bronchopneumopathy, subjected to mechanical ventilation and sedated with remifentanil. The sample was then compared with another 2 groups (homogeneous with the first) of 20 patients each, treated with propofol and midazolam as the only drug. Following an initial bolus of 2 mg/kg (+/-0.04) for propofol and 0.15 mg/kg (+/-0.03) for midazolam (no bolus for remifentanil), the doses of subsequent continuous infusion (initial doses in the case of remifentanil) were: 0.05 mcg/kg/m (+/-0.01) for remifentanil; 1 mg/kg/h (+/-0.04) for propofol; 0.03 mg/kg/h (+/-0.006) for midazolam. In order to assess the level and quality of sedation, 2 subjective evaluation scales (Ramsey score and the Sedation-Agitation Score: SAS) and one system of objective evaluation (Bispectral Index; BIS) were employed. The BIS is a direct measure of the effects of anaesthetics on the brain. It is represented by a single digit (between 100, state of arousal, and zero, EEG flat), derived statistically and empirically from the EEG. RESULTS: No significant differences were encountered as regards quality of sedation among the 3 groups but there was a significant difference in negative cardiovascular activity in patients treated with propofol (12% reduction in Cl, 13.8% reduction in SVR). A significant accumulation of the drug was observed in cases treated with midazolam, whereas there was no accumulation for remifentanil and propofol in relation to the duration of the infusion. CONCLUSIONS: Of the various sedation modalities employed, we prefer the one which uses remifentanil as the sole drug because a good level of sedation is obtained, there is no accumulation, little interference with cardiovascular parameters and lower costs in comparison with the others.