Our Heritage, the Soil

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Rate of photosynthetic induction in fluctuating light varies widely among genotypes of wheat.

Crop photosynthesis and yield are limited by slow photosynthetic induction in sunflecks. We quantified variation in induction kinetics across diverse genotypes of wheat for the first time. Following a preliminary study that hinted at wide variation in induction kinetics across 58 genotypes, we grew 10 genotypes with contrasting responses in a controlled environment and quantified induction kinetics of carboxylation capacity (Vcmax) from dynamic A versus ci curves after a shift from low to high light (from 50 µmol m-2 s-1 to 1500 µmol m-2 s-1), in five flag leaves per genotype. Within-genotype median time for 95% induction (t95) of Vcmax varied 1.8-fold, from 5.2 min to 9.5 min. Our simulations suggest that non-instantaneous induction reduces daily net carbon gain by up to 15%, and that breeding to speed up Vcmax induction in the slowest of our 10 genotypes to match that in the fastest genotype could increase daily net carbon gain by up to 3.4%, particularly for leaves in mid-canopy positions (cumulative leaf area index ≤1.5 m2 m-2), those that experience predominantly short-duration sunflecks, and those with high photosynthetic capacities

The Role of a University Archives in Producing a History of a Core Curriculum

During an annual alumni weekend celebration, librarians at a liberal arts college rely heavily on the university’s archival collection to produce a robust exhibit on the university’s history. The 2014 exhibit focused on the unique academic program, known as the Core Curriculum. The history produced for this exhibit depended on documents from the 1940s to the 1990s, including university publications, papers, and project reports created by faculty members. Starting with one publication, The Oglethorpe Book, the variations on and reactions to this sole document provide a paper trail of historical significance in defining and redefining a college core program. The importance of a university archives and the preservation of its historical materials are clearly articulated in this brief but significant history

Citizens of somewhere: examining the geography of foreign and native-born academics’ engagement with external actors

This paper explores the geography of academic engagement patterns of native and foreign-born academics, contrasting how patterns of intranational and international engagement with non-academic actors differ between these two groups. We suggest that foreign-born academics will engage more internationally than their native-born colleagues, whereas native-born academics will have greater levels of intranational engagement. Drawing upon a large multi-source dataset, including a major new survey of all academics working the UK, we find support for this idea that where people are born influences how they engage with non-academic actors. We also find that these differences are attenuated by an individual’s intranational and international experience, ethnicity and language skills. We explore the implications of these findings for policy to support intranational and international academic engagement.The Arts and Humanities Research Council, the Department for Business, Innovation & Skills, the Economic and Social Research Council, the Engineering and Physical Sciences Research Council, the Higher Education Funding Council for England, the Medical Research Council, and the Natural Environment Research Council and the National Centre for Universities and Business (NCUB). Cornelia Lawson received support from the University of Bath through a Prize fellowship

Radio Synchrotron Emission from Secondary Leptons in the Vicinity of Sgr A*

A point-like source of ~TeV gamma-rays has recently been seen towards the Galactic center by HESS and other air Cerenkov telescopes. In recent work (Ballantyne et al. 2007), we demonstrated that these gamma-rays can be attributed to high-energy protons that (i) are accelerated close to the event horizon of the central black hole, Sgr A*, (ii) diffuse out to ~pc scales, and (iii) finally interact to produce gamma-rays. The same hadronic collision processes will necessarily lead to the creation of electrons and positrons. Here we calculate the synchrotron emissivity of these secondary leptons in the same magnetic field configuration through which the initiating protons have been propagated in our model. We compare this emission with the observed ~GHz radio spectrum of the inner few pc region which we have assembled from archival data and new measurements we have made with the Australia Telescope Compact Array. We find that our model predicts secondary synchrotron emission with a steep slope consistent with the observations but with an overall normalization that is too large by a factor of ~ 2. If we further constrain our theoretical gamma-ray curve to obey the implicit EGRET upper limit on emission from this region we predict radio emission that is consistent with observations, i.e., the hadronic model of gamma ray emission can, simultaneously and without fine-tuning, also explain essentially all the diffuse radio emission detected from the inner few pc of the Galaxy.Comment: 11 pages, 2 figures. Two references missing from published version added and acknowledgements extende

Census estimates of algal and epiphytic carbonate production highlight tropical seagrass meadows as sediment production hotspots

This is the author accepted manuscript. The final version is available from Frontiers Media via the DOI in this record.Tropical shelf, platform and reef-lagoon systems are dominated by calcium carbonate (CaCO3) sediments. However, data on habitat-specific CaCO3 sediment production rates by different sediment producing taxa are sparse, limiting understanding of where and in what form CaCO3 sediment is produced, and how overall sediment budgets are influenced by habitat type and scale. Using novel census methodologies, based primarily on measures of plant biovolumes and carbonate content, we assessed habitat-scale production by two ubiquitous biogenic CaCO3 sediment producers, calcareous green algae and seagrass epiphytes, across southern Eleuthera Bank, Bahamas (area ~140 km2). Data from species-specific plant disaggregation experiments and from X-ray diffraction (XRD) analysis of calcified plants also allowed us to resolve questions about the size fractions and mineralogies of the carbonates produced. Production rates varied significantly among habitats (range: 1.8–237.3 g CaCO3 m-2 yr-1), collectively totalling ~0.98 M kg annually across the study area. Outputs comprise similar amounts of aragonite and high Mg-calcite, with ~54% of the CaCO3 produced being contributed as mud-grade (<63 μm) sediment. Our analysis also reveals that habitat type and extent - especially of medium and high density seagrass beds - strongly influence the amounts and types of carbonate sediment generated. Dense seagrass beds were identified as the dominant per unit area production sites, contributing ~17% of total CaCO3 despite covering only 0.5% of the study area. These findings have direct relevance for quantifying present-day sediment budgets and for predicting changes in sediment generation at the system scale in responses to modified habitat extent and productivity.Natural Environment Research Council (NERC

The role of diatom resting spores in pelagic–benthic coupling in the Southern Ocean

Natural iron fertilization downstream of Southern Ocean island plateaus supports large phytoplankton blooms and promotes carbon export from the mixed layer. In addition to sequestering atmospheric CO2, the biological carbon pump also supplies organic matter (OM) to deep-ocean ecosystems. Although the total flux of OM arriving at the seafloor sets the energy input to the system, the chemical nature of OM is also of significance. However, a quantitative framework linking ecological flux vectors to OM composition is currently lacking. In the present study we report the lipid composition of export fluxes collected by five moored sediment traps deployed in contrasting productivity regimes of Southern Ocean island systems (Kerguelen, Crozet and South Georgia) and compile them with quantitative data on diatom and faecal pellet fluxes. At the three naturally iron-fertilized sites, the relative contribution of labile lipids (mono- and polyunsaturated fatty acids, unsaturated fatty alcohols) is 2–4 times higher than at low productivity sites. There is a strong attenuation of labile components as a function of depth, irrespective of productivity. The three island systems also display regional characteristics in lipid export. An enrichment of zooplankton dietary sterols, such as C27Δ5, at South Georgia is consistent with high zooplankton and krill biomass in the region and the importance of faecal pellets to particulate organic carbon (POC) flux. There is a strong association of diatom resting spore fluxes that dominate productive flux regimes with energy-rich unsaturated fatty acids. At the Kerguelen Plateau we provide a statistical framework to link seasonal variation in ecological flux vectors and lipid composition over a complete annual cycle. Our analyses demonstrate that ecological processes in the upper ocean, e.g. resting spore formation and grazing, not only impact the magnitude and stoichiometry of the Southern Ocean biological pump, but also regulate the composition of exported OM and the nature of pelagic–benthic coupling