Guillain-Barré syndrome (GBS) is the most common cause of acute flaccid paralysis (AFP) in the post-poliomyelitis eradication era. This is the first study done to identify the epidemiology, clinical features, and outcome of GBS in Iraqi children over 15 years.
Methods
The surveillance database about AFP cases?<?15 years reported during January 1997-December 2011 was used.
Results
GBS represented 52.5% of AFP cases, with an incidence of 1.33 case/100,000 population?<?15 years/year. There was a higher incidence in the Southern provinces, age group 1–4 years, males, and outside the capital city of province, with no significant seasonal variations (p?=?.22). Survival probability after the 1 year of onset for those with respiratory muscle involvement was .76 (95% CI: .60-.86), versus .97 (95% Cl: .96-.98) for those who did not develop it (p?<?.001); and .97 (95% CI: .96-.98) for those living inside the capital city, versus .94 (.93-.95) for those living outside (p?=?.001). Cumulative incidence of residual paralysis for patients living inside the capital city was .21 (95% CI: .18-.24), versus .27 (95% CI: .25-.29) for those living outside (p?<?.001).
Conclusions
The incidence, age and gender distribution, and seasonality of GBS among Iraqi children is similar to those reported from other previous studies. It is the most important cause of AFP, especially in those between the age of 1 to 4 years living in rural areas.
Total denitrification and nitrous oxide (N2O) losses were measured from three contrasting dairy management systems representing good commercial practice (system 1), production maintained but with reduced N losses (system 2); and nitrate leaching less than 50 mg L-1 but with reduced production (system 3). Measurements were made following mineral fertiliser application and from two plot experiments where four treatments were applied: control, NH4NO3 at 60 kg N ha-1, cattle slurry applied to the surface (equivalent to 45 kg N ha-1), and cattle slurry injected. Despite low soil temperatures (<6 °C) and low rainfall (<3 mm), total denitrification and N2O losses peaked at 56 and 16 g N ha-1 d-1, respectively. Total denitrification losses decreased: system 1 system 2 > system 3, whereas N2O losses decreased: system 2 > system 3 > system 1. Total denitrification losses tended to decrease with decreasing fertiliser application rate, whereas fertiliser application rate was not the sole determinant of the N2O loss. The system 3 field was injected with cattle slurry for 2 yr, system 2 received some slurry by injection and system 1 received slurry to the surface. Thus, the amount, timing and method of previous cattle slurry application was important in determining the loss following subsequent fertiliser application. For the plot experiments, total denitrification and N2O losses decreased in the order: slurry injected > mineral fertiliser > slurry applied to the surface > control for 5 days following application. However, 16 and 19 days after application, N2O losses above the control were measured from plots that had received cattle slurry. It was inferred that the application of cattle slurry to the pasture soil stimulated greater N2O production and increased losses over a longer time period compared with mineral fertiliser additions. 相似文献
Signatories of the Kyoto Protocol are obliged to submit annual accounts of their anthropogenic greenhouse gas emissions, which include nitrous oxide (N(2)O). Emissions from the sectors industry (3.8 Gg), energy (14.4 Gg), agriculture (86.8 Gg), wastewater (4.4 Gg), land use, land-use change and forestry (2.1 Gg) can be calculated by multiplying activity data (i.e. amount of fertilizer applied, animal numbers) with simple emission factors (Tier 1 approach), which are generally applied across wide geographical regions. The agricultural sector is the largest anthropogenic source of N(2)O in many countries and responsible for 75 per cent of UK N(2)O emissions. Microbial N(2)O production in nitrogen-fertilized soils (27.6 Gg), nitrogen-enriched waters (24.2 Gg) and manure storage systems (6.4 Gg) dominate agricultural emission budgets. For the agricultural sector, the Tier 1 emission factor approach is too simplistic to reflect local variations in climate, ecosystems and management, and is unable to take into account some of the mitigation strategies applied. This paper reviews deviations of observed emissions from those calculated using the simple emission factor approach for all anthropogenic sectors, briefly discusses the need to adopt specific emission factors that reflect regional variability in climate, soil type and management, and explains how bottom-up emission inventories can be verified by top-down modelling. 相似文献
Soils are an important source of N2O, which can be produced both in the nitrification and the denitrification processes. Grassland soils in particular have a high potential for mineralization and subsequent nitrification and denitrification. When ploughing long term grassland soils, the resulting high supply of mineral N may provide a high potential for N2O losses. In this work, the short-term effect of ploughing a permanent grassland soil on gaseous N production was studied at different soil depths. Fertiliser and irrigation were applied in order to observe the effect of ploughing under a range of conditions. The relative proportions of N2O produced from nitrification and denitrification and the proportion of N2 gas produced from denitrification were determined using the methyl fluoride and acetylene specific inhibitors. Irrespectively to ploughing, fertiliser application increased the rates of N2O production, N2O production from nitrification, N2O production from denitrification and total denitrification (N2O + N2). Application of fertiliser also increased the denitrification N2O/N2 ratio both in the denitrification potential and in the gaseous N productions by denitrification. Ploughing promoted soil organic N mineralization which led to an increase in the rates of N2O production, N2O production from nitrification, N2O production from denitrification and total denitrification (N2O + N2). In both the ploughed and unploughed treatments the 0–10 cm soil layer was the major contributing layer to gaseous N production by all the above processes. However, the contribution of this layer decreased by ploughing, gaseous N productions from the 10 to 30 cm layer being significantly increased with respect to the unploughed treatment. Ploughing promoted both nitrification and denitrification derived N2O production, although a higher proportion of N2O lost by denitrification was observed as WFPS increased. Recently ploughed plots showed lower denitrification derived N2O percentages than those ploughed before as a result of the lower soil water content in the former plots. Similarly, a lower mean nitrification derived N2O percentage was found in the 10–30 cm layer compared with the 0–10 cm. 相似文献
Miniaturized bubble columns (MBCs) have different hydrodynamics in comparison with the larger ones, but there is a lack of scientific data on MBCs. Hence, in this study, the effect of gas hold-up, flow regimes, bubble size distribution on volumetric oxygen mass transfer coefficient at different pore size spargers and gas flow rates in MBCs in the presence and absence of microorganisms were investigated. It was found that flow regime transition occurred around low gas flow rates of 1.18 and 0.85 cm/s for small (16–40 µm) and large (40–100 µm) pore size spargers, respectively. Gas hold-up and KLa in MBC with small size sparger were higher than those with larger one, with an increasing effect in the presence of microorganisms. A comparison revealed that the wall effect on the flow regime and gas hold-up in MBCs was greater than bench-scale bubble columns. The KLa values significantly increased up to tenfold using small pore size sparger. In the MBC and stirred tank bioreactors, the maximum obtained cell concentrations were OD600 of 41.5 and 43.0, respectively. Furthermore, it was shown that in MBCs, higher KLa and lower turbulency could be achieved at the end of bubbly flow regime.
Nitrous oxide (N2O) is a potent greenhouse gas with a high contribution from agricultural soils and emissions that depend on soil type, climate,
crops and management practices. The N2O emissions therefore need to be included as an integral part of environmental assessments of agricultural production systems.
An algorithm for N2O production and emission from agricultural soils was developed and included in the FASSET whole-farm model. The model simulated
carbon and nitrogen (N) turnover on a daily basis. Both nitrification and denitrification was included in the model as sources
for N2O production, and the N2O emissions depended on soil microbial and physical conditions. The model was tested on experimental data of N2O emissions from grasslands in UK, Finland and Denmark, differing in climatic conditions, soil properties and management.
The model simulated the general time course of N2O emissions and captured the observed effects of fertiliser and manure management on emissions. Scenario analyses for grazed
and cut grasslands were conducted to evaluate the effects of soil texture, climatic conditions, grassland management and N
fertilisation on N2O emissions. The soils varied from coarse sand to sandy loam and the climatic variation was taken to represent the climatic
variation within Denmark. N fertiliser rates were varied from 0 to 500 kg N ha−1. The simulated N2O emissions showed a non-linear response to increasing N rates with increasing emission factors at higher N rates. The simulated
emissions increased with increasing soil clay contents. N2O emissions were slightly increased at higher temperatures, whereas increasing annual rainfall generally lead to decreasing
emissions. Emissions were slightly higher from grazed grasslands compared with cut grasslands at similar rates of total N
input (fertiliser and animal excreta). The results indicate higher emission factors and thus higher potentials for reducing
N2O emissions for intensively grazed grasslands on fine textured soils than for extensive cut-based grasslands on sandy soils. 相似文献
This article evaluates the suitability of the ECOSSE model to estimate soil greenhouse gas (GHG) fluxes from short rotation coppice willow (SRC‐Willow), short rotation forestry (SRF‐Scots Pine) and Miscanthus after land‐use change from conventional systems (grassland and arable). We simulate heterotrophic respiration (Rh), nitrous oxide (N2O) and methane (CH4) fluxes at four paired sites in the UK and compare them to estimates of Rh derived from the ecosystem respiration estimated from eddy covariance (EC) and Rh estimated from chamber (IRGA) measurements, as well as direct measurements of N2O and CH4 fluxes. Significant association between modelled and EC‐derived Rh was found under Miscanthus, with correlation coefficient (r) ranging between 0.54 and 0.70. Association between IRGA‐derived Rh and modelled outputs was statistically significant at the Aberystwyth site (r =0.64), but not significant at the Lincolnshire site (r =0.29). At all SRC‐Willow sites, significant association was found between modelled and measurement‐derived Rh (0.44 ≤ r ≤0.77); significant error was found only for the EC‐derived Rh at the Lincolnshire site. Significant association and no significant error were also found for SRF‐Scots Pine and perennial grass. For the arable fields, the modelled CO2 correlated well just with the IRGA‐derived Rh at one site (r =0.75). No bias in the model was found at any site, regardless of the measurement type used for the model evaluation. Across all land uses, fluxes of CH4 and N2O were shown to represent a small proportion of the total GHG balance; these fluxes have been modelled adequately on a monthly time‐step. This study provides confidence in using ECOSSE for predicting the impacts of future land use on GHG balance, at site level as well as at national level. 相似文献