12165 research outputs found
Sort by
The impact of evaluations on academic careers. An study of academics in four disciplines, four countries and three cohorts.
No full text
Seasonal and vertical distribution of putative ammonia-oxidizing thaumarchaeotal communities in an oligotrophic lake
No full textThe discovery of Archaea carrying an amoA gene coding for the A-subunit of ammonia monooxygenase gave a boost to studies aimed at detecting this gene under diverse conditions. Despite numerous studies describing the archaeal amoA gene abundance and richness in different habitats, the understanding of the freshwater ecology of potentially archaeal ammonia oxidizers, recently positioned in the phylum Thaumarchaeota, is still lacking. In a seasonal and vertical study of deep oligotrophic Lake Lucerne, Switzerland, with high Thaumarchaeota-specific crenarchaeol concentrations, we showed that all archaeal 16S rRNA genes found belong to the thaumarchaeotal phylum. The abundances of archaeal 16S rRNA and amoA genes remained in the same order of magnitude (average 6 × mL−1) and displayed matching seasonal dynamics within 16 monthly collected samples at three different water depths (r2 = 0.80, slope of 1.06). The Thaumarchaeota in this lake form a distinct cluster in both the 16S rRNA and amoA gene phylogenies, are affiliated to other thaumarchaeotal freshwater sequences within group 1.1a Archaea, and fall in the low saline cluster of the amoA phylogeny. In accordance with temperature and conductivity, the Thaumarchaeota in the surface water showed a significantly different seasonality and lower abundance than their counterparts in the deeper waters. This study indicates that the ecology of Thaumarchaeota, with their potential in nitrogen cycling, may differ per water depth in deep freshwater ecosystems.
“Aanstotelijke uijtdrukkingen” en andere zaken die we kunnen leren uit de gekaapte brieven
No full text
Structural and functional variation in soil fungal communities associated with litter bags containing maize
No full textBrent goose colonies near snowy owls: Internest distances in relation to breeding arctic fox densities
No full textIt was shown that in the years when the numbers of the Arctic foxes are high, even though the lemming numbers are high as well, Brent geese nest considerably closer to owls' nests than in the years with low Arctic fox numbers. At values of the Arctic fox densities greater than one breeding pair per 20 km(2), the factor of lemming numbers ceases to affect the distance between owl and geese nests. This distance becomes dependent on the Arctic fox density (numbers). When the Arctic fox density is greater than the pronounced threshold, the owl-Brent internest distance is inversely and linearly related to the Arctic fox density. DOI: 10.1134/S106235901301007X [KEYWORDS: rough-legged buzzards peregrine falcons taimyr peninsula lemmings]