4,211 research outputs found

    A Selection from Mexican Studies

    Get PDF

    Patricia H. Marks, Deconstructing Legitimacy: Viceroys, Merchants, and the Military in Late Colonial Peru

    Get PDF

    John R. Fisher, Bourbon Peru, 1750-1824

    Get PDF

    An Essay on the Mexican Viceroys During the War of Independence: The Question of Legitimacy*

    Get PDF

    JULES-BE:Representation of bioenergy crops and harvesting in the Joint UK Land Environment Simulator vn5.1

    Get PDF
    We describe developments to the land surface model JULES, allowing for flexible user-prescribed harvest regimes of various perennial bioenergy crops or natural vegetation types. Our aim is to integrate the most useful aspects of dedicated bioenergy models into dynamic global vegetation models, in order that assessment of bioenergy options can benefit from state-of-the-art Earth system modelling. A new plant functional type (PFT) representing Miscanthus is also presented. The Miscanthus PFT fits well with growth parameters observed at a site in Lincolnshire, UK; however, global observed yields of Miscanthus are far more variable than is captured by the model, primarily owing to the model's lack of representation of crop age and establishment time. Global expansion of bioenergy crop areas under a 2 ?C emissions scenario and balanced greenhouse gas mitigation strategy from the IMAGE integrated assessment model (RCP2.6- SSP2) achieves a mean yield of 4.3 billion tonnes of dry matter per year over 2040-2099, around 30 % higher than the biomass availability projected by IMAGE. In addition to perennial grasses, JULES-BE can also be used to represent short-rotation coppicing, residue harvesting from cropland or forestry and rotation forestry

    Towards the general mechanistic prediction of community dynamics

    Get PDF
    ”What controls the distribution and abundance of organisms”? This question, at the heart of the dynamics of ecological communities, would have been familiar to the earliest ecologists. Having lain effectively abandoned for many years, community dynamics today is a vibrant research topic of great conceptual interest with practical import for conservation, ecological management, ecosystem services and the responses of ecological communities to climate change.  We describe how modern coexistence theory can be applied to predict community dynamics through the use of demography. We explore the challenges that limit the deployment of this demographic framework, and the tools from phylogenetic and functional ecology that have been used to surmount them.  Finding existing tools not altogether sufficient, we propose the use of ‘hard’ functional traits and physiological tolerances of environmental conditions and low resource availability to extend the demographic framework so that the dynamics of a broader range of ecological communities can be accurately predicted.  We illustrate these new approaches with two case studies. Given the urgent need to accurately forecast the dynamics of ecological communities, we hope that many ecologists will adopt these tools

    Towards Integrative Systematics of Anthozoa (Cnidaria): Evolution of Form in the Order Zoanthidea

    Get PDF
    A decade of research inferring evolutionary relationships from nucleotide sequences has demonstrated a fundamental misconception of the evolution of form in Zoanthidea. Morphological features that define current taxa are plesiomorphic or homoplastic and do not circumscribe clades of species delineated by ecological and molecular characters. Although molecular data have been critical in exposing this deficiency, their parataxonomic application to Zoanthidea has created a barrier to comprehensive revision within the order. Species descriptions and higher taxon definitions based on nucleotide sequences isolate new taxa from the existing taxonomic system and restrict the application of novel systematics hypotheses to a fraction of the known diversity of taxa. This creates competing taxonomic systems that do not benefit from the knowledge contained in the opposing system. To enable the integration of modern molecular data with more than a century of morphological research, characters that can simultaneously span the parataxonomy barrier, existing taxonomic system and historical record must be identified. Here, we test the utility of morphological characters for integrative systematics by reviewing commonly described and novel morphological characters, assessing independence of character components and analysing character homoplasy and ancestral states on the most comprehensive molecular phylogeny available. The results indicate a rich diversity of form that span the full range of homoplasy values, including more than a dozen independent characters useful to systematics or differentiating closely related species. The least homoplasious characters include traditionally targeted (fifth mesenteries, marginal muscle arrangement, encircling sinus) and novel (fissure morphology, basal canals of the mesenteries) features. These analyses represent a first step in identifying characters necessary for reunification and revision of Zoanthidea systematics

    New Detections of Arsenic, Selenium, and Other Heavy Elements in Two Metal-Poor Stars

    Get PDF
    We use the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope to obtain new high-quality spectra covering the 1900 to 2360 Angstrom wavelength range for two metal-poor stars, HD 108317 and HD 128279. We derive abundances of Cu II, Zn II, As I, Se I, Mo II, and Cd II, which have not been detected previously in either star. Abundances derived for Ge I, Te I, Os II, and Pt I confirm those derived from lines at longer wavelengths. We also derive upper limits from the non-detection of W II, Hg II, Pb II, and Bi I. The mean [As/Fe] ratio derived from these two stars and five others in the literature is unchanged over the metallicity range -2.8 = +0.28 +/- 0.14 (std. dev. = 0.36 dex). The mean [Se/Fe] ratio derived from these two stars and six others in the literature is also constant, = +0.16 +/- 0.09 (std. dev. = 0.26 dex). The As and Se abundances are enhanced relative to a simple extrapolation of the iron-peak abundances to higher masses, suggesting that this mass region (75 < A < 82) may be the point at which a different nucleosynthetic mechanism begins to dominate the quasi-equilibrium alpha-rich freezeout of the iron peak. = +0.56 +/- 0.23 in HD 108317 and HD 128279, and we infer that lines of Cu I may not be formed in local thermodynamic equilibrium in these stars. The [Zn/Fe], [Mo/Fe], [Cd/Fe], and [Os/Fe] ratios are also derived from neutral and ionized species, and each ratio pair agrees within the mutual uncertainties, which range from 0.15 to 0.52 dex.Comment: Accepted for publication in the Astrophysical Journal. 13 pages, 10 figure

    Detection of the Second r-process Peak Element Tellurium in Metal-Poor Stars

    Get PDF
    Using near-ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope, we detect neutral tellurium in three metal-poor stars enriched by products of r-process nucleosynthesis, BD+17 3248, HD 108317, and HD 128279. Tellurium (Te, Z=52) is found at the second r-process peak (A=130) associated with the N=82 neutron shell closure, and it has not been detected previously in Galactic halo stars. The derived tellurium abundances match the scaled solar system r-process distribution within the uncertainties, confirming the predicted second peak r-process residuals. These results suggest that tellurium is predominantly produced in the main component of the r-process, along with the rare earth elements.Comment: Accepted for publication in the Astrophysical Journal Letters (5 pages, 2 figures

    Hubble Space Telescope Near-Ultraviolet Spectroscopy of the Bright CEMP-no Star BD+44 493

    Full text link
    We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the extremely metal-poor star BD+44 493, a 9th magnitude sub-giant with [Fe/H] = -3.8 and enhanced carbon, based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This star is the brightest example of a class of objects that, unlike the great majority of carbon-enhanced metal-poor (CEMP) stars, does not exhibit over-abundances of heavy neutron-capture elements (CEMP-no). In this paper, we validate the abundance determinations for a number of species that were previously studied in the optical region, and obtain strong upper limits for beryllium and boron, as well as for neutron-capture elements from zirconium to platinum, many of which are not accessible from ground-based spectra. The boron upper limit we obtain for BD+44 493, logeps(B) < -0.70, the first such measurement for a CEMP star, is the lowest yet found for very and extremely metal-poor stars. In addition, we obtain even lower upper limits on the abundances of beryllium, logeps(Be) < -2.3, and lead, logeps(Pb) < -0.23 ([Pb/Fe] < +1.90), than those reported by previous analyses in the optical range. Taken together with the previously measured low abundance of lithium, the very low upper limits on Be and B suggest that BD+44 493 was formed at a very early time, and that it could well be a bona-fide second-generation star. Finally, the Pb upper limit strengthens the argument for non-s-process production of the heavy-element abundance patterns in CEMP-no stars.Comment: 18 pages, 12 figures; accepted for publication in Ap
    • 

    corecore