Statistical modelling and prediction of pollutants in the urban atmosphere of Salamanca, Spain

 The primary aim of the present work is to describe and analyze the temporal trends of concurrent hourly observations and its daily averaged series of the pollutants CO, NO₂, NO and SO₂ in the urban area of the City of Salamanca (environmental survey station SA001) for the period between 1 December 1993 and 30 November 1994. Using daily series corresponding to different meteorological variables recorded at the same site for the same period (wind direction, relative humidity, pressure, radiation, temperature and wind speed), linear regression techniques are used to study the relationships of these variables with each of the polluntants on both an individual and multivariate basis. The results obtained explain 40% of the variance of the series for NO₂ and 66% in the case of SO₂. Finally, in the modelling phase it was observed that the series of polluntants themselves have sufficient ’’information’’ to enable, by means of autoregressive and integrated moving average techniques (A.R.I.M.A.), the determination of future pollution. Once predicted, these were contrasted with the measured or observed values to check the goodness of the model. Received: 9 December 1996 / Accepted: 24 January 1997     

A Reassessment of Prebiotic Organic Synthesis in Neutral Planetary Atmospheres

The action of an electric discharge on reduced gas mixtures such as H₂O, CH₄ and NH₃ (or N₂) results in the production of several biologically important organic compounds including amino acids. However, it is now generally held that the early Earth’s atmosphere was likely not reducing, but was dominated by N₂ and CO₂. The synthesis of organic compounds by the action of electric discharges on neutral gas mixtures has been shown to be much less efficient. We show here that contrary to previous reports, significant amounts of amino acids are produced from neutral gas mixtures. The low yields previously reported appear to be the outcome of oxidation of the organic compounds during hydrolytic workup by nitrite and nitrate produced in the reactions. The yield of amino acids is greatly increased when oxidation inhibitors, such as ferrous iron, are added prior to hydrolysis. Organic synthesis from neutral atmospheres may have depended on the oceanic availability of oxidation inhibitors as well as on the nature of the primitive atmosphere itself. The results reported here suggest that endogenous synthesis from neutral atmospheres may be more important than previously thought. Stanley L. Miller died May 20, 2007.     

Factors of influence on microbial pollution in the atmosphere over Beijing area

Summary The atmospheric microbial pollutants are potentially correlated to population density and activity as well as to human health. The higher the population density is, the heavier the air microbial pollution will become. Some meteorological factors exert great influence on air microbial pollution. Generally, wind, solar radiation and rainfalls purify air and, consequently cause a decrease in atmospheric microbial pollution. On the other hand, prevailing strong winds may favour this pollution, especially in dry conditions and in absence of vegetation. Obviously, relatively high temperatures associated with high RH enhance the growing of microbes. However, the higher the temperature is, the lower the viability of airborne microbes will be; nonetheless, with high RH a decrease in suspended particles may be recorded.     

Air-surface exchange measurement in heterogeneous regions: extending tower observations with spatial structure observed from small aircraft

Strategies to assess long-term atmosphere-ecosystem exchange of CO₂ and H₂O must deal not only with time trends but also with spatial variability. Flux towers efficiently measure time trends, but only at discrete sites, always limited in number. Representativeness of these sites and the causes of spatial variation between sites are difficult to investigate from tower data alone. Such issues are better addressed with flux measurements from moving vehicles, particularly aircraft. Recent technological advancements in aircraft and instrumentation now allow mobile flux measurement with enhanced precision, greater ease, and lower cost. Results are presented which illustrate the importance of spatial variability, and some suggestions are given for assessment of flux-tower representativeness. Unfortunately, airborne observations of the kind presented here are practical only during a part of the daylight hours in brief intensive field campaigns. Extrapolation of spatial-structure information derived from these measurements to night-time or to long-term averages thus remains problematic. For the foreseeable future this extrapolation will require models that faithfully simulate both space and time characteristics of H₂O and CO₂ exchange. The development and validation of such models will be greatly enhanced by the increased availability of measurements from moving vehicles, which record spatial as well as temporal structure.     

High Thyrotropin Levels and Risk of Mortality in the Elderly With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis

ObjectiveThis study aims to determine whether elevated endogenous thyrotropin levels contribute to an increased risk of adverse outcomes, such as all-cause mortality in older adults with subclinical hypothyroidism.MethodsEight electronic databases were searched for relevant articles from inception until March 23, 2022. Cohort studies assessing the association between thyrotropin levels and the risk of mortality among older adults aged ≥60 years with subclinical hypothyroidism were eligible. The outcomes of interest were either all-cause or cardiovascular-related mortality. Two independent researchers assessed the eligibility of the studies and collected data through a previously defined data extraction form. The Newcastle-Ottawa Scale was used to evaluate the quality of evidence, and multivariate-adjusted hazard ratios (HRs) (95% Cl) were collected as the necessary risk estimate for synthesis. Random-effects models were applied for meta-analysis.ResultsOverall, 13 studies involving 44 514 participants were included in this meta-analysis. There were no significant differences in the risk of all-cause mortality (pooled HR: 1.18 [95% Cl: 0.95, 1.45], I² = 94%) and cardiovascular-related mortality (pooled HR: 1.08 [95% Cl: 0.94, 1.23], I² = 0%) between euthyroid older adults and older adults with subclinical hypothyroidism. The results remained the same when only older adults with thyrotropin ≥10 mIU/L were assessed (pooled HR for all-cause mortality and cardiovascular-related mortality, respectively: 1.53 [95% Cl: 0.81, 2.88], I² = 22%, 1.35 [95% Cl: 0.63, 2.86], I² = 43%).ConclusionHigh thyrotropin levels are not associated with increased risk for all-cause mortality as well as cardiovascular-related mortality in older adults aged ≥60 years with subclinical hypothyroidism, suggesting an unnecessity in initialing treatment.