530 research outputs found

    Fish for the city: meta-analysis of archaeological cod remains and the growth of London’s northern trade

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    The growth of medieval cities in Northern Europe placed new demands on food supply, and led to the import of fish from increasingly distant fishing grounds. Quantitative analysis of cod remains from London provides revealing insight into the changing patterns of supply that can be related to known historical events and circumstances. In particular it identifies a marked increase in imported cod from the thirteenth century AD. That trend continued into the fifteenth and sixteenth centuries, after a short downturn, perhaps attributable to the impact of the Black Death, in the mid fourteenth century. The detailed pattern of fluctuating abundance illustrates the potential of archaeological information that is now available from the high-quality urban excavations conducted in London and similar centres during recent decades

    Unit organization of the topic, business letters in first-year typewriting.

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    Thesis (M.A.)--Boston Universit

    Stories from the city, stories from the sea

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    In an ingenious study that draws on decades of excavation, archaeologists asked what bones might tell us about past cod consumption in London. The result is a striking insight into medieval fish trade and the globalisation of the city’s food suppl

    The Origin of Nitrogen on Jupiter and Saturn from the 15^{15}N/14^{14}N Ratio

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    The Texas Echelon cross Echelle Spectrograph (TEXES), mounted on NASA's Infrared Telescope Facility (IRTF), was used to map mid-infrared ammonia absorption features on both Jupiter and Saturn in February 2013. Ammonia is the principle reservoir of nitrogen on the giant planets, and the ratio of isotopologues (15^{15}N/14^{14}N) can reveal insights into the molecular carrier (e.g., as N2_2 or NH3_3) of nitrogen to the forming protoplanets, and hence the source reservoirs from which these worlds accreted. We targeted two spectral intervals (900 and 960 cm−1^{-1}) that were relatively clear of terrestrial atmospheric contamination and contained close features of 14^{14}NH3_3 and 15^{15}NH3_3, allowing us to derive the ratio from a single spectrum without ambiguity due to radiometric calibration (the primary source of uncertainty in this study). We present the first ground-based determination of Jupiter's 15^{15}N/14^{14}N ratio (in the range from 1.4×10−31.4\times10^{-3} to 2.5×10−32.5\times10^{-3}), which is consistent with both previous space-based studies and with the primordial value of the protosolar nebula. On Saturn, we present the first upper limit on the 15^{15}N/14^{14}N ratio of no larger than 2.0×10−32.0\times10^{-3} for the 900-cm−1^{-1} channel and a less stringent requirement that the ratio be no larger than 2.8×10−32.8\times10^{-3} for the 960-cm−1^{-1} channel (1σ1\sigma confidence). Specifically, the data rule out strong 15^{15}N-enrichments such as those observed in Titan's atmosphere and in cometary nitrogen compounds. To the extent possible with ground-based radiometric uncertainties, the saturnian and jovian 15^{15}N/14^{14}N ratios appear indistinguishable, implying that 15^{15}N-enriched ammonia ices could not have been a substantial contributor to the bulk nitrogen inventory of either planet, favouring the accretion of primordial N2_2 from the gas phase or as low-temperature ices.Comment: 33 pages, 19 figures, manuscript accepted for publication in Icaru

    Animal bones [from Nebelivka]

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    In this book, a team of international authors examines the hypothesis of independent Eastern European urbanism using the evidence gathered from the multi-disciplinary investigation of the Trypillia megasite of Nebelivka

    Fish for London

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    Previous synthesis of zooarchaeological remains from English medieval sites has shown that marine fish consumption increased, from a very low baseline, around ad 1000, a phenomenon dubbed the fish event horizon (FEH) by Barrett et al. (2004a). This change appears initially to have been linked primarily to urban sites, with widespread marine fish consumption at inland rural settlements argued to be a slightly later development (Barrett et al. 2004b; but see also Chapter 17 regarding near-coastal elite settlements). That early towns and cities led the way in the expansion of marine resource use is perhaps unsurprising, given that urban settlements almost by de nition involve a concentration of food consumers rather than producers and hence require a signi cant hinterland to meet demand. Turning to marine resources is one way to expand this resource base

    Hysteretic thermal spin-crossover in heteroleptic Fe(II) complexes using alkyl chain substituted 2,2’-dipyridylamine ligands

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    The alkyl chain carrying ligands N,N-di(pyridin-2-yl)butanamide (LC4) and N,N-di(pyridin-2-yl)decanamide (LC10) were combined with NCS− co-ligands to form the neutral heteroleptic Fe(II) complexes trans-[FeII(LC4)2(NCS)2] (1C4) and trans-[FeII(LC10)2(NCS)2] (1C10). Variable temperature crystallographic studies revealed that 1C4 is in the orthorhombic space group Pna21 between 85–200 K whereas 1C10 is in the monoclinic space group P21/c between 85–140 K. The average Fe–N bond lengths suggest that at 85 K 1C4 contains LS Fe(II) centres; however, the ca. 0.18 Å increase in the average Fe–N bond lengths between 85 and 120 K suggests a spin-transition to the HS state occurs within this temperature interval. 1C10 contains LS Fe(II) centres between 85 and 105 K. Upon warming from 105 to 140 K the average Fe–N bond lengths increase by ca. 0.19 Å, which suggests a spin-transition to the HS state. Solid-state magnetic susceptibility measurements showed that 1C4 undergoes semi-abrupt spin-crossover with T1/2 = 127.5 K and a thermal hysteresis of ca. 13 K whereas, 1C10 undergoes an abrupt spin-crossover with T1/2 = 119.0 K, and is also accompanied by thermal hysteresis of ca. 4 K. The crystallographic and magnetic data show that the length of the complex's alkyl chain substituents can have a large impact on the structure of the crystal lattice as well as a subtle effect on the T1/2 value for thermal spin-crossover

    2,7-Bis(pyridin-3-ylethynyl)fluoren-9-one

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    2,7-bis(pyridin-3-ylethynyl)fluoren-9-one [(3-PyE)2FO] was synthesized in one step by the Sonogashira coupling reaction between 3-ethynylpyridine and 2,7-dibromofluoren-9-one. The title compound was fully characterized, and its crystal structure was determined through single-crystal XRD analysis

    Saturn's Seasonal Variability from Four Decades of Ground-Based Mid-Infrared Observations

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    A multi-decade record of ground-based mid-infrared (7-25 μ\mum) images of Saturn is used to explore seasonal and non-seasonal variability in thermal emission over more than a Saturnian year (1984-2022). Thermal emission measured by 3-m and 8-m-class observatories compares favourably with synthetic images based on both Cassini-derived temperature records and the predictions of radiative climate models. 8-m class facilities are capable of resolving thermal contrasts on the scale of Saturn's belts, zones, polar hexagon, and polar cyclones, superimposed onto large-scale seasonal asymmetries. Seasonal changes in brightness temperatures of ∼30\sim30 K in the stratosphere and ∼10\sim10 K in the upper troposphere are observed, as the northern and southern polar stratospheric vortices (NPSV and SPSV) form in spring and dissipate in autumn. The timings of the first appearance of the warm polar vortices is successfully reproduced by radiative climate models, confirming them to be radiative phenomena, albeit entrained within sharp boundaries influenced by dynamics. Axisymmetric thermal bands (4-5 per hemisphere) display temperature gradients that are strongly correlated with Saturn's zonal winds, indicating winds that decay in strength with altitude, and implying meridional circulation cells forming the system of cool zones and warm belts. Saturn's thermal structure is largely repeatable from year to year (via comparison of infrared images in 1989 and 2018), with the exception of low-latitudes. Here we find evidence of inter-annual variations because the equatorial banding at 7.9 μ\mum is inconsistent with a ∼15\sim15-year period for Saturn's equatorial stratospheric oscillation, i.e., it is not strictly semi-annual. Finally, observations between 2017-2022 extend the legacy of the Cassini mission, revealing the continued warming of the NPSV during northern summer. [Abr.]Comment: 25 pages, 15 figures, accepted for publication in Icaru

    Hazy Blue Worlds:A Holistic Aerosol Model for Uranus and Neptune, Including Dark Spots

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    We present a reanalysis (using the Minnaert limb-darkening approximation) of visible/near-infrared (0.3 - 2.5 micron) observations of Uranus and Neptune made by several instruments. We find a common model of the vertical aerosol distribution that is consistent with the observed reflectivity spectra of both planets, consisting of: 1) a deep aerosol layer with a base pressure > 5-7 bar, assumed to be composed of a mixture of H2S ice and photochemical haze; 2) a layer of photochemical haze/ice, coincident with a layer of high static stability at the methane condensation level at 1-2 bar; and 3) an extended layer of photochemical haze, likely mostly of the same composition as the 1-2-bar layer, extending from this level up through to the stratosphere, where the photochemical haze particles are thought to be produced. For Neptune, we find that we also need to add a thin layer of micron-sized methane ice particles at ~0.2 bar to explain the enhanced reflection at longer methane-absorbing wavelengths. We suggest that methane condensing onto the haze particles at the base of the 1-2-bar aerosol layer forms ice/haze particles that grow very quickly to large size and immediately 'snow out' (as predicted by Carlson et al. 1988), re-evaporating at deeper levels to release their core haze particles to act as condensation nuclei for H2S ice formation. In addition, we find that the spectral characteristics of 'dark spots', such as the Voyager-2/ISS Great Dark Spot and the HST/WFC3 NDS-2018, are well modelled by a darkening or possibly clearing of the deep aerosol layer only.Comment: 58 pages, 23 figures, 4 table
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