A ten year study of the incidence of spores of bracken, (Pteridium aquilinum (L.) Kuhn.) in an urban rooftop airstream in south east Scotland

Field studies of bracken during sporing haveindicated very high numbers of sporesreleased per cubic metre of air. Thecarcinogenic nature of bracken spores poses ahealth hazard to workers and visitors in areasof sporing strands.A retrospective study of bracken spores trappedon slides exposed during Augustand September over the ten year period, 1988–1997, on a rooftop site in Edinburgh,has added an urban dimension to the aerobiologyof bracken.Results have revealed, apart from 1989,consistently low counts. The spore samplerwas situated downwind approximately 1.6 km fromthe nearest sporing stand.A spore calendar, based on the ten years ofcumulative data, has been constructed.     

Analysis of the methane production in thermophilic anaerobic reactors: use of autofluorescence microscopy

Methanogenic activity in thermophilic, anaerobic reactors was determined by comparing the amount of methane generated in single- and two-stage systems with the size of the methanogenic population, as determined by microscopy. The methanogenic activities were 2.71 × 10^–9 ml methane cell^–1 d^–1 and 1.10 × 10^–9 ml methane cell^–1 d^–1 for 10 and 4 days of the hydraulic retention time (HRT), in the single-stage system. In the two-stage system, 7.49 × 10^–9 ml methane cell^–1 d^–1 in the acidogenic reactor and 1.56 × 10^–9 ml methane cell^–1 d^–1 in the methanogenic reactor for 4 days of the HRT. A high correlation was evident between the methane production and methanogenic population [0.1354 ln(x) – 2.1375](R ² 0.8619).     

Effects of Pharmacological Concentrations of Dietary Zinc Oxide on Growth of Post-weaning Pigs: A Meta-analysis

Pharmacological dietary zinc (Zn) concentrations of 1,000 to 3,000 mg/kg diet from Zn oxide have been found to increase growth in post-weaning pigs. However, results were inconsistent among studies. A frequentist meta-analysis, in which effects were numerically described with standardized effect sizes (Hedges's g), was conducted in order to identify and quantify the responses in average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G/F) in post-weaning pigs upon dietary Zn supplementation from Zn oxide. The inability of independent continuous variables to explain significant heterogeneity obtained with fixed effect models necessitated the use of random effects models to calculate summary statistics. Dietary Zn supplementation increased (P?<?0.05) ADG (mean effect size?=?1.086, 95 % confidence intervals?=?0.905–1.266, 26 studies, 72 comparisons), ADFI (mean effect size?=?0.794, 95 % confidence intervals?=?0.616–0.971, 25 studies, 71 comparisons), and G/F (mean effect size?=?0.566, 95 % confidence intervals?=?0.422–0.710, 24 studies, 70 comparisons). Zinc oxide provided a feasible alternative to in-feed antibiotics to improve growth in post-weaning pigs, and its reduction in diets due to potential environmental pollution will have to be negated by alternative feed additives and management strategies in order to prevent economic losses.