Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation

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Retrieval of a million high-quality, full-length microbial 16S and 18S rRNA gene sequences without primer bias

Small subunit ribosomal RNA (SSU rRNA) genes, 16S in bacteria and 18S in eukaryotes, have been the standard phylogenetic markers used to characterize microbial diversity and evolution for decades. However, the reference databases of full-length SSU rRNA gene sequences are skewed to well-studied ecosystems and subject to primer bias and chimerism, which results in an incomplete view of the diversity present in a sample. We combine poly(A)-tailing and reverse transcription of SSU rRNA molecules with synthetic long-read sequencing to generate high-quality, full-length SSU rRNA sequences, without primer bias, at high throughput. We apply our approach to samples from seven different ecosystems and obtain more than a million SSU rRNA sequences from all domains of life, with an estimated raw error rate of 0.17%. We observe a large proportion of novel diversity, including several deeply branching phylum-level lineages putatively related to the Asgard Archaea. Our approach will enable expansion of the SSU rRNA reference databases by orders of magnitude, and contribute to a comprehensive census of the tree of life

An outline of indirect holographic methods for antenna measurements and microwave imaging

Indirect microwave holographic techniques offer a simple, low cost technique for a range of microwave measurements including the determination of antenna characteristics and the ability to provide good quality images of passive objects. This work provides a brief outline of the basic theory of indirect microwave holography and how it can be used for the reconstruction of scattered complex fields at the measurement plane and how these results can be back propagated to provide the scattered fields at any preselected observation plane. It provides an outline of the different techniques required for antenna measurement and the imaging of passive objects. It demonstrates how indirect holography can be used to determine the far field radiation pattern of a high gain antenna and reconstruct the complex antenna aperture fields. This work also demonstrates the use of indirect holography for the imaging of passive objects. The techniques described have been validated by experimental results on a range of objects including buried objects