Contribution of crop model structure,parameters and climate projections to uncertainty in climate change impact assessments

Climate change impact assessments are plagued with uncertainties from many sources, such as climate projections or the inadequacies in structure and parameters of the impact model. Previous studies tried to account for the uncertainty from one or two of these. Here, we developed a triple‐ensemble probabilistic assessment using seven crop models, multiple sets of model parameters and eight contrasting climate projections together to comprehensively account for uncertainties from these three important sources. We demonstrated the approach in assessing climate change impact on barley growth and yield at Jokioinen, Finland in the Boreal climatic zone and Lleida, Spain in the Mediterranean climatic zone, for the 2050s. We further quantified and compared the contribution of crop model structure, crop model parameters and climate projections to the total variance of ensemble output using Analysis of Variance (ANOVA). Based on the triple‐ensemble probabilistic assessment, the median of simulated yield change was ?4% and +16%, and the probability of decreasing yield was 63% and 31% in the 2050s, at Jokioinen and Lleida, respectively, relative to 1981–2010. The contribution of crop model structure to the total variance of ensemble output was larger than that from downscaled climate projections and model parameters. The relative contribution of crop model parameters and downscaled climate projections to the total variance of ensemble output varied greatly among the seven crop models and between the two sites. The contribution of downscaled climate projections was on average larger than that of crop model parameters. This information on the uncertainty from different sources can be quite useful for model users to decide where to put the most effort when preparing or choosing models or parameters for impact analyses. We concluded that the triple‐ensemble probabilistic approach that accounts for the uncertainties from multiple important sources provide more comprehensive information for quantifying uncertainties in climate change impact assessments as compared to the conventional approaches that are deterministic or only account for the uncertainties from one or two of the uncertainty sources.     

Seasonal variation in CH4 emissions and production and oxidation potentials at microsites on an oligotrophic pine fen

 Temporal and spatial variation in CH₄ emissions was studied at hummock, Eriophorum lawn, flark and Carex lawn microsites in an oligotrophic pine fen over the growing season using a static chamber method, and CH₄ production and oxidation potentials in peat profiles from hummock and flark were determined in laboratory incubation experiments. Emissions were lowest in the hummocks, and decreased with increasing hummock height, while in the lawns and flarks they increased with increasing sedge cover. Statistical response functions with water table and peat temperature as independent variables were calculated in order to reconstruct seasonal CH₄ emissions by reference to the time series for peat temperature and water table specific to each microsite type. Mean CH₄ emissions in the whole area in the snow-free period of 1993, weighted in terms of the proportions of the microsites, were 1.7 mol CH₄ m^–2. Potential CH₄ production and oxidation rates were very low in the hummocks rising above the groundwater table, but were relatively similar when expressed per dry weight of peat both in the hummocks and flarks below the water table. The CH₄ production potential increased in autumn at both microsites and CH₄ oxidation potential seemed to decrease. The decrease in temperature in autumn certainly reduced in situ decomposition processes, possibly leaving unused substrates in the peat, which would explain the increase in CH₄ production potential. Received: 16 August 1996 / Accepted: 30 November 1996     

Oral health and morbidity--implications of oral infections on the elderly

Detrimental effects of oral infections on general health have been known for almost 3000 years. Modern studies, however, have cast new light on the pathogenic mechanisms by which oral infections appear to link with morbidity and mortality. In particular, among the elderly, poor dental health seems to associate with all-cause mortality. This review aims to provide an overview of present knowledge of these issues, starting from dental bacteraemia, oral mucosal infections and problems of drug resistance and, briefly, discussing what is known about the link between oral health and some systemic diseases such as atherosclerosis and type-2 diabetes. The main conclusions are that scientific evidence is still weak on these interactions and that the elderly should be better taken into account when planning future studies. Functions of the body differ in the frail and diseased from those of the young. Consequently, novel prevention and treatment strategies should be developed and properly tested for combating oral infections in elderly populations. Specific suggestions for further research are outlined.     

Polyacrylamide lamination enables mass spectrometry compatible staining and in-gel digestion of proteins separated by agarose IEF

Agarose IEF enables the separation of large proteins and protein complexes. A complication of agarose gels attached onto polyester support is the lack of sensitive protein staining methods compatible with protein analysis and identification protocols. In this study, agarose IEF gels were used to separate the proteins, followed by layering the agarose with polyacrylamide. The formed laminate gels were seamless and durable and they were readily detached from the polyester. The gels were amenable to MS compatible staining. The sensitivity obtained with the acidic silver staining method was 20-50 ng/band of myoglobin. Laminated agarose was a suitable matrix for in-gel digestion based generation of tryptic peptides for MALDI-MS.     

Afforestation does not necessarily reduce nitrous oxide emissions from managed boreal peat soils

Pristine peatlands have generally low nitrous oxide (N₂O) emissions but drainage and management practices enhance the microbial processes and associated N₂O emissions. It is assumed that leaving peat soils from intensive management, such as agriculture, will decrease their N₂O emissions. In this paper we report how the annual N₂O emission rates will change when agricultural peat soil is either left abandoned or afforested and also N₂O emissions from afforested peat extraction sites. In addition, we evaluated a biogeochemical model (DNDC) with a view to explaining GHG emissions from peat soils under different land uses. The abandoned agricultural peat soils had lower mean annual N₂O emissions (5.5?±?5.4?kg?N?ha^?1) than the peat soils in active agricultural use in Finland. Surprisingly, N₂O emissions from afforested organic agricultural soils (12.8?±?9.4?kg?N?ha^?1) were similar to those from organic agricultural soils in active use. These emissions were much higher than those from the forests on nutrient rich peat soils. Abandoned and afforested peat extraction sites emitted more N₂O, (2.4?±?2.1?kg?N?ha^?1), than the areas under active peat extraction (0.7?±?0.5?kg?N?ha^?1). Emissions outside the growing season contributed significantly, 40% on an average, to the annual emissions. The DNDC model overestimated N₂O emission rates during the growing season and indicated no emissions during winter. The differences in the N₂O emission rates were not associated with the age of the land use change, vegetation characteristics, peat depth or peat bulk density. The highest N₂O emissions occurred when the soil C:N ratio was below 20 with a significant variability within the measured C:N range (13–27). Low soil pH, high nitrate availability and water table depth (50–70?cm) were also associated with high N₂O emissions. Mineral soil has been added to most of the soils studied here to improve the fertility and this may have an impact on the N₂O emissions. We infer from the multi-site dataset presented in this paper that afforestation is not necessarily an efficient way to reduce N₂O emissions from drained boreal organic fields.     

Exhaled pentane as a possible marker for survival and lipid peroxidation during radiotherapy for lung cancer—a pilot study

To examine lipid peroxidation during radiotherapy (RT), exhaled pentane samples were collected from 11 lung cancer patients before RT and 30 and 120 min after the start of RT on days 1, 4 and 5 and at 30 and 40 Grays, if possible. Exhaled pentane samples were collected once from 30 healthy controls. Serum thiobarbituric-acid-reactive substances (TBARS) and conjugated dienes (CD) were obtained from patients on each exhaled air collection day. Lung cancer patients had higher exhaled pentane levels than controls (1.73 ng/L vs 0.83 ng/L, p=0.017). Exhaled pentane levels tended to decrease during the first RT day (p=0.075) and levels of CD decreased during the first week of RT (p=0.014). Higher pre-treatment pentane levels predicted better survival (p=0.003). Elevated exhaled pentane levels before RT may be due to the lipid peroxidation burden associated with cancer. The decrease of lipid peroxidation markers during RT may be attributable to enhanced antioxidant defense mechanisms.