Empirically determined decision levels development and use in an in vivo bioassay program

This paper discusses a method to empirically determine and a use for reporting a decision level value for {sup 137}Cs using a Canberra Accuscan II, direct radiobioassay (in vivo) system. The decision level value is used to determine the upper 5% of in vivo measurements for the purpose of recounting individuals. The paper overviews decision level concepts, the applicability of ANSI N13.30 and ANSI N42.2 and describes the specific process employed

Laser-annealing Josephson junctions for yielding scaled-up superconducting quantum processors

As superconducting quantum circuits scale to larger sizes, the problem of frequency crowding proves a formidable task. Here we present a solution for this problem in fixed-frequency qubit architectures. By systematically adjusting qubit frequencies post-fabrication, we show a nearly ten-fold improvement in the precision of setting qubit frequencies. To assess scalability, we identify the types of 'frequency collisions' that will impair a transmon qubit and cross-resonance gate architecture. Using statistical modeling, we compute the probability of evading all such conditions, as a function of qubit frequency precision. We find that without post-fabrication tuning, the probability of finding a workable lattice quickly approaches 0. However with the demonstrated precisions it is possible to find collision-free lattices with favorable yield. These techniques and models are currently employed in available quantum systems and will be indispensable as systems continue to scale to larger sizes.Comment: 9 pages, 6 figures, Supplementary Information. Update to correct typo in author name and in text. Updated acknowledgements and corrected typo in acknowledgement

Maximum rates of N2 fixation and primary production are out of phase in a developing cyanobacterial bloom in the Baltic Sea

Although N2-fixing cyanobacteria contribute significantly to oceanic sequestration of atmospheric CO2, little is known about how N2 fixation and carbon fixation (primary production) interact in natural populations of marine cyanobacteria. In a developing cyanobacterial bloom in the Baltic Sea, rates of N2 fixation (acetylene reduction) showed both diurnal and longer-term fluctuations. The latter reflected fluctuations in the nitrogen status of the cyanobacterial population and could be correlated with variations in the ratio of acetylene reduced to 15N2 assimilated. The value of this ratio may provide useful information about the release of newly fixed nitrogen by a cyanobacterial population. However, although the diurnal fluctuations in N2 fixation broadly paralleled diurnal fluctuations in carbon fixation, the longer-term fluctuations in these two processes were out of phase

Metabolic variability in seafloor brines revealed by carbon and sulphur dynamics

Brine fluids that upwell from deep, hot reservoirs below the sea bed supply the sea floor with energy-rich substrates and nutrients that are used by diverse microbial ecosystems. Contemporary hypersaline environments formed by brine seeps may provide insights into the metabolism and distribution of microorganisms on the early Earth or on extraterrestrial bodies. Here we use geochemical and genetic analyses to characterize microbial community composition and metabolism in two seafloor brines in the Gulf of Mexico: an active mud volcano and a quiescent brine pool. Both brine environments are anoxic and hypersaline. However, rates of sulphate reduction and acetate production are much higher in the brine pool, whereas the mud volcano supports much higher rates of methane production. We find no evidence of anaerobic oxidation of methane, despite high methane fluxes at both sites. We conclude that the contrasting microbial community compositions and metabolisms are linked to differences in dissolved-organic-matter input from the deep subsurface and different fluid advection rates between the two sites. DOI: 10.1038/NGEO47

Screening of DUB activity and specificity by MALDI-TOF mass spectrometry

Deubiquitylases (DUBs) are key regulators of the ubiquitin system which cleave ubiquitin moieties from proteins and polyubiquitin chains. Several DUBs have been implicated in various diseases and are attractive drug targets. We have developed a sensitive and fast assay to quantify in vitro DUB enzyme activity using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Unlike other current assays, this method uses unmodified substrates, such as diubiquitin topoisomers. By analyzing 42 human DUBs against all diubiquitin topoisomers we provide an extensive characterization of DUB activity and specificity. Our results confirm the high specificity of many members of the OTU and JAMM DUB families and highlight that all USPs tested display low linkage selectivity. We also demonstrate that this assay can be deployed to assess the potency and specificity of DUB inhibitors by profiling 11 compounds against a panel of 32 DUBs

Multipurpose acoustic networks in the integrated arctic ocean observing system

The dramatic reduction of sea ice in the Arctic Ocean will increase human activities in the coming years. This activity will be driven by increased demand for energy and the marine resources of an Arctic Ocean accessible to ships. Oil and gas exploration, fisheries, mineral extraction, marine transportation, research and development, tourism, and search and rescue will increase the pressure on the vulnerable Arctic environment. Technologies that allow synoptic in situ observations year-round are needed to monitor and forecast changes in the Arctic atmosphere-ice-ocean system at daily, seasonal, annual, and decadal scales. These data can inform and enable both sustainable development and enforcement of international Arctic agreements and treaties, while protecting this critical environment. In this paper, we discuss multipurpose acoustic networks, including subsea cable components, in the Arctic. These networks provide communication, power, underwater and under-ice navigation, passive monitoring of ambient sound (ice, seismic, biologic, and anthropogenic), and acoustic remote sensing (tomography and thermometry), supporting and complementing data collection from platforms, moorings, and vehicles. We support the development and implementation of regional to basin-wide acoustic networks as an integral component of a multidisciplinary in situ Arctic Ocean observatory