Deep carbon storage potential of buried floodplain soils.

Soils account for the largest terrestrial pool of carbon and have the potential for even greater quantities of carbon sequestration. Typical soil carbon (C) stocks used in global carbon models only account for the upper 1 meter of soil. Previously unaccounted for deep carbon pools (>1 m) were generally considered to provide a negligible input to total C contents and represent less dynamic C pools. Here we assess deep soil C pools associated with an alluvial floodplain ecosystem transitioning from agricultural production to restoration of native vegetation. We analyzed the soil organic carbon (SOC) concentrations of 87 surface soil samples (0-15 cm) and 23 subsurface boreholes (0-3 m). We evaluated the quantitative importance of the burial process in the sequestration of subsurface C and found our subsurface soils (0-3 m) contained considerably more C than typical C stocks of 0-1 m. This deep unaccounted soil C could have considerable implications for global C accounting. We compared differences in surface soil C related to vegetation and land use history and determined that flooding restoration could promote greater C accumulation in surface soils. We conclude deep floodplain soils may store substantial quantities of C and floodplain restoration should promote active C sequestration

Unusual light spectra from a two-level atom in squeezed vacuum

We investigate the interaction of an atom with a multi-channel squeezed vacuum. It turns out that the light coming out in a particular channel can have anomalous spectral properties, among them asymmetry of the spectrum, absence of the central peak as well as central hole burning for particular parameters. As an example plane-wave squeezing is considered. In this case the above phenomena can occur for the light spectra in certain directions. In the total spectrum these phenomena are washed out.Comment: 16 pages, LaTeX, 3 figures (included via epsf

An Analysis of the Origins of Ontology Mismatches on the Semantic Web

Despite the potential of domain ontologies to provide consensual representations of domain-relevant knowledge, the open, distributed and decentralized nature of the Semantic Web means that individuals will rarely, if ever, countenance a common set of terminological and representational commitments during the ontology design process. More often than not, differences between ontologies are likely to occur, and this is the case even when the ontologies describe identical or overlapping domains of interest. Differences between ontologies are often referred to as ontology mismatches and there is an extensive research literature geared towards the technology-mediated reconciliation of such mismatches. Our approach in the current paper is not to comment on the relative merits or demerits of the various technological solutions that could be used to resolve ontological differences; rather, we aim to explore the reasons why such differences may arise in the first place. In addition to a review of the various factors that contribute to ontology mismatches on the Semantic Web, we also discuss a number of focus areas for future research in this area. An improved understanding of the origins of ontology mismatches will, we argue, complement existing research into semantic integration techniques. In particular, by understanding more about the complex cognitive, epistemic and socio-cultural factors associated with the ontology development process, we may be able to develop knowledge acquisition and modeling tools/techniques that attenuate the impact of ontology mismatches for large-scale information sharing and data integration on the Semantic Web

The Gaia Ultra-Cool Dwarf Sample -- II : Structure at the end of the main sequence

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We identify and investigate known late M, L, and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultracool dwarfs work package. We find 695 objects in the optical spectral range M8–T6 with accurate Gaia coordinates, proper motions, and parallaxes which we combine with published spectral types and photometry from large area optical and infrared sky surveys. We find that 100 objects are in 47 multiple systems, of which 27 systems are published and 20 are new. These will be useful benchmark systems and we discuss the requirements to produce a complete catalogue of multiple systems with an ultracool dwarf component. We examine the magnitudes in the Gaia passbands and find that the G BP magnitudes are unreliable and should not be used for these objects. We examine progressively redder colour–magnitude diagrams and see a notable increase in the main-sequence scatter and a bivariate main sequence for old and young objects. We provide an absolute magnitude – spectral subtype calibration for G and G RP passbands along with linear fits over the range M8–L8 for other passbands.Peer reviewedFinal Published versio

Shock tunnel studies of scramjet phenomena, supplement 6

Reports by the staff of the University of Queensland on various research studies related to the advancement of scramjet technology are presented. These reports document the tests conducted in the reflected shock tunnel T4 and supporting research facilities that have been used to study the injection, mixing, and combustion of hydrogen fuel in generic scramjets at flow conditions typical of hypersonic flight. In addition, topics include the development of instrumentation and measurement technology, such as combustor wall shear and stream composition in pulse facilities, and numerical studies and analyses of the scramjet combustor process and the test facility operation

Cosmic ray tables - Asymptotic directions, variational coefficients and cut-off rigidities IQSY instruction manual no. 10

Cosmic ray deflections in geomagnetic field, variational coefficients, and diurnal intensity variations - table

Reversible Intercalation of Fluoride-Anion Receptor Complexes in Graphite

We have demonstrated a route to reversibly intercalate fluoride-anion receptor complexes in graphite via a nonaqueous electrochemical process. This approach may find application for a rechargeable lithium–fluoride dual-ion intercalating battery with high specific energy. The cell chemistry presented here uses graphite cathodes with LiF dissolved in a nonaqueous solvent through the aid of anion receptors. Cells have been demonstrated with reversible cathode specific capacity of approximately 80 mAh/g at discharge plateaus of upward of 4.8 V, with graphite staging of the intercalant observed via in situ synchrotron X-ray diffraction during charging. Electrochemical impedance spectroscopy and 11B nuclear magnetic resonance studies suggest that co-intercalation of the anion receptor with the fluoride occurs during charging, which likely limits the cathode specific capacity. The anion receptor type dictates the extent of graphite fluorination, and must be further optimized to realize high theoretical fluorination levels. To find these optimal anion receptors, we have designed an ab initio calculations-based scheme aimed at identifying receptors with favorable fluoride binding and release properties

Differences in Carbon Sequestration and Water Use Between a Semi-Arid Native Grassland and Encroaching \u3ci\u3eVachellia karroo\u3c/i\u3e Woodland

Tree and shrub encroachment and proliferation in global grasslands and savannas is widely considered to imply a trade-off between ecosystem C and H2O regulating functions, based on the premise that increased C sequestration associated with higher woody biomass ostensibly drive declines in water production through concomitant increases in evapotranspiration (ET), but evidence for this across climatic and environmental gradients is equivocal. To evaluate these claims, we ran a paired eddy covariance experiment in a native semi-arid C4 grassland and adjacent encroaching Vachellia karroo woodland on the eastern seaboard of South Africa and compared ecosystem C and H2O budgets over nearly a full year. Near complete failure of spring/early summer rains resulted in reduced ecosystem physiological activity and C uptake in the early growing season in 2019, but systems recovered following above average rainfall over mid-summer/early autumn in 2020, with both the grassland and woodland achieving net negative C balances. The woodland was more productive than the grassland over the majority of the year, but these marginal C gains were offset by consistently higher respiration effluxes, resulting in the grassland sequestering significantly more C (197. 6 g C m-1) than the woodland (114.5 g C m-1). Differences in water use between the two systems were insignificant, and is likely explained by shallow soils and the absence of subsurface water at the site, which largely negated the competitive advantage in terms of access to water conferred by deeper rooting systems of V. karroo. Ecosystem water use efficiencies (WUEE) were essentially identical across the year, but the grassland was more efficient at the peak of the growing season. Our data suggest that encroachment by V. karroo in semi-arid grasslands may result in significant declines in C sequestration despite higher rates of productivity, but is unlikely to lead to substantial increases in water use where trees do not have access to water in deeper soil horizons on the other. These results support growing arguments to preserve semi-arid grassland ecosystems even when C sequestration is the primary objective of land management interventions