1,240 research outputs found
Metagenome skimming of insect specimen pools: potential for comparative genomics
Metagenomic analyses are challenging in metazoans, but high-copy number and repeat regions can be assembled from lowcoverage
sequencing by âgenome skimming,â which is applied here as a new way of characterizing metagenomes obtained in an ecological or taxonomic context. Illumina shotgun sequencing on two pools of Coleoptera (beetles) of approximately 200 species each were assembled into tens of thousands of scaffolds. Repeated low-coverage sequencing recovered similar scaffold sets consistently, although approximately 70% of scaffolds could not be identified against existing genome databases. Identifiable scaffolds included mitochondrial DNA, conserved sequences with hits to expressed sequence tag and protein databases, and knownrepeatelementsof high and low complexity, includingnumerous copies ofrRNAandhistone genes.Assemblies of histones captured a diversity of gene order and primary sequence in Coleoptera. Scaffolds with similarity to multiple sites in available coleopteran genome sequences for Dendroctonus and Tribolium revealed high specificity of scaffolds to either of these genomes,
in particular for high-copy number repeats. Numerous âclustersâ of scaffolds mapped to the same genomic site revealed intraand/or intergenomic variation within a metagenome pool. In addition to effect of taxonomic composition of the metagenomes, the number of mapped scaffolds also revealed structural differences between the two reference genomes, although the significance of this striking finding remains unclear. Finally, apparently exogenous sequences were recovered, including potential food plants, fungal pathogens, and bacterial symbionts. The âmetagenome skimmingâ approach is useful for capturing the genomic diversity of poorly studied, species-rich lineages and opens new prospects in environmental genomic
Experimental feedback control of quantum systems using weak measurements
A goal of the emerging field of quantum control is to develop methods for
quantum technologies to function robustly in the presence of noise. Central
issues are the fundamental limitations on the available information about
quantum systems and the disturbance they suffer in the process of measurement.
In the context of a simple quantum control scenario--the stabilization of
non-orthogonal states of a qubit against dephasing--we experimentally explore
the use of weak measurements in feedback control. We find that, despite the
intrinsic difficultly of implementing them, weak measurements allow us to
control the qubit better in practice than is even theoretically possible
without them. Our work shows that these more general quantum measurements can
play an important role for feedback control of quantum systems.Comment: 4 pages, 3 figures. v2 Added extra citation, journal reference and
DOI. Minor typographic correction
Sustainability in social enterprise: hybrid organizing in public services
It is commonly assumed that social enterprises (SEs) are able to meet social outcomes and also be financially viable; however, little research supports this claim. Using hybrid organizing as a lens to analyse case study interview data from ten SEs delivering adult day-care services, we identify three factors which affect an SEâs ability to simultaneously achieve social outcomes and financial sustainability and thus create value-spillovers for society. These are diverse income streams to strengthen financial viability and reduce reliance on service-level agreements and grants; delivering social quality (quality of social impact) as well as service quality, and a hybrid workforce
Modeling the climate impact of Southern Hemisphere ozone depletion:the importance of the ozone dataset
The ozone hole is an important driver of recent Southern Hemisphere (SH) climate change, and capturing these changes is a goal of climate modeling. Most climate models are driven by off-line ozone data sets. Previous studies have shown that there is a substantial range in estimates of SH ozone depletion, but the implications of this range have not been examined systematically. We use a climate model to evaluate the difference between using the ozone forcing (Stratospheric Processes and their Role in Climate (SPARC)) used by many Intergovernmental Panel on Climate Change Fifth Assessment Report (Coupled Model Intercomparison Project) models and one at the upper end of the observed depletion estimates (Binary Database of Profiles (BDBP)). In the stratosphere, we find that austral spring/summer polar cap cooling, geopotential height decreases, and zonal wind increases in the BDBP simulations are all doubled compared to the SPARC simulations, while tropospheric responses are 20â100% larger. These results are important for studies attempting to diagnose the climate fingerprints of ozone depletion
Thirty Meter Telescope Site Testing I: Overview
As part of the conceptual and preliminary design processes of the Thirty
Meter Telescope (TMT), the TMT site testing team has spent the last five years
measuring the atmospheric properties of five candidate mountains in North and
South America with an unprecedented array of instrumentation. The site testing
period was preceded by several years of analyses selecting the five candidates,
Cerros Tolar, Armazones and Tolonchar in northern Chile; San Pedro Martir in
Baja California, Mexico and the 13 North (13N) site on Mauna Kea, Hawaii. Site
testing was concluded by the selection of two remaining sites for further
consideration, Armazones and Mauna Kea 13N. It showed that all five candidates
are excellent sites for an extremely large astronomical observatory and that
none of the sites stands out as the obvious and only logical choice based on
its combined properties. This is the first article in a series discussing the
TMT site testing project.Comment: Accepted for publication in PASP, April 2009 issu
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