2,604 research outputs found

    Human activity was a major driver of the mid-Holocene vegetation change in southern Cumbria: Implications for the elm decline in the British Isles

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The dramatic decline in elm (Ulmus) across a large swathe of north-west Europe in the mid-Holocene has been ascribed to a number of possible factors, including climate change, human activity and/or pathogens. A major limitation for identifying the underlying cause(s) has been the limited number of high-resolution records with robust geochronological frameworks. Here, we report a multiproxy study of an upland (Blea Tarn) and lowland (Urswick Tarn) landscape in southern Cumbria (British Isles) to reconstruct vegetation change across the elm decline in an area with a rich and well-dated archaeological record to disentangle different possible controls. Here we find a two-stage decline in Ulmus taking place between 6350–6150 and 6050–5850 cal a BP, with the second phase coinciding with an intensification of human activity. The scale of the decline and associated human impact is more abrupt in the upland landscape. We consider it likely that a combination of human impact and disease drove the Ulmus decline within southern Cumbria.This work was funded by a studentship for MJG from the University of Exeter and Sir John Fisher Foundation. Additional funding for 14C dating was from the Cumberland and Westmorland Antiquarian and Archaeological Society (Clare Fell Bursary to MJG), and the Australian Research Council (FL100100195)

    The preparation, identification and properties of chlorophyll derivatives

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    In the investigation of 10-hydroxy chlorophylls a and b novel techniques included modification of chromatography and the use of fully-deuterated compounds isolated from fully-deuterated autotropic algae to determine the molecular structure of the chlorophylls

    Dreamy Swanee Lullaby

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    With Ukulele arrangement. Contains advertisements and/or short musical examples of pieces being sold by publisher.https://digitalcommons.library.umaine.edu/mmb-vp/6987/thumbnail.jp

    State and Local Anti-Predatory Lending Laws: The Effect of Legal Enforcement Mechanisms

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    Subprime mortgage lending has grown rapidly in recent years and with it, so have concerns about predatory lending. In response to evidence of predatory lending, most states have enacted new laws or expanded existing laws to address abuses in the subprime home loan market. The effect of these statutes is a matter of debate. This paper seeks to improve the understanding of this increasingly important issue and pays particular attention to the role that legal enforcement mechanisms play in this context. The results of the analysis are consistent with the view that anti-predatory lending laws influence subprime lending markets and that disaggregating the details of the overall legal framework into its component parts is essential for understanding subprime market dynamics. The restrictions, coverage, and enforcement components all have significant relationships with subprime market outcomes, with the coverage relationship found to be broadly consistent with the reverse lemons hypothesis put forward by Ho and Pennington-Cross (2007). The results also suggest that the newer mini-HOEPA laws have had an impact on the subprime market above and beyond the older preexisting laws, particularly for subprime originations. Broader coverage through these new laws is associated with higher origination likelihoods, while increased restrictions through the mini-HOEPA laws are associated with lower origination propensities

    The Impact of State Anti-Predatory Lending Laws: Policy Implications and Insights

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    The subprime mortgage market, which consists of high-cost loans designed for borrowers with weak credit, has grown tremendously over the past ten years. Between 1993 and 2005, the subprime market experienced an average annual growth rate of 26 percent. As this market emerged, so did allegations that subprime loans contained predatory features or were the result of predatory sales practices.3 In the worst cases, brokers deceived borrowers about the meaning of loan terms or falsely promised to assist them in obtaining future refinance loans with better terms. In other situations, borrowers entered into loans with low teaser rates, not aware how high their monthly payments could go when their interest rates reset

    Acoustic Waveform Logging - Advances In Theory And Application

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    Full-waveform acoustic logging has made significant advances in both theory and application in recent years, and these advances have greatly increased the capability of log analysts to measure the physical properties of formations. Advances in theory provide the analytical tools required to understand the properties of measured seismic waves, and to relate those properties to such quantities as shear and compressional velocity and attenuation, and primary and fracture porosity and permeability of potential reservoir rocks. The theory demonstrates that all parts of recorded waveforms are related to various modes of propagation, even in the case of dipole and quadrupole source logging. However, the theory also indicates that these mode properties can be used to design velocity and attenuation picking schemes, and shows how source frequency spectra can be selected to optimize results in specific applications. Synthetic microseismogram computations are an effective tool in waveform interpretation theory; they demonstrate how shear arrival picks and mode attenuation can be used to compute shear velocity and intrinsic attenuation, and formation permeability for monopole, dipole and quadrupole sources. Array processing of multi-receiver data offers the opportunity to apply even more sophisticated analysis techniques. Synthetic microseismogram data is used to illustrate the application of the maximum-likelihood method, semblance cross-correlation, and Prony's method analysis techniques to determine seismic velocities and attenuations. The interpretation of acoustic waveform logs is illustrated by reviews of various practical applications, including synthetic seismogram generation, lithology determination, estimation of geomechanical properties in situ, permeability estimation, and design of hydraulic fracture operations

    NMR relaxation rates for the spin-1/2 Heisenberg chain

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    The spin-lattice relaxation rate 1/T11/T_1 and the spin echo decay rate 1/T2G1/T_{2G} for the spin-121\over 2 antiferromagnetic Heisenberg chain are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are compared with recent analytical calculations by Sachdev. If the nuclear hyperfine form factor AqA_q is strongly peaked around q=πq=\pi the predicted low-temperature behavior [1/T1ln1/2(1/T)1/T_1 \sim \ln{^{1/2}(1/T)}, 1/T2Gln1/2(1/T)/T1/T_{2G} \sim \ln{^{1/2}(1/T)}/\sqrt{T}] extends up to temperatures as high as T/J0.5T/J \approx 0.5. If AqA_q has significant weight for q0q \approx 0 there are large contributions from diffusive long-wavelength processes not taken into account in the theory, and very low temperatures are needed in order to observe the asymptotic T0T \to 0 forms.Comment: 9 pages, Revtex 3.0, 5 uuencoded ps figures To appear in Phys. Rev. B, Rapid Com

    Exclusive Decuplet-Baryon Pair Production in Two-Photon Collisions

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    This work extends our previous studies of two-photon annihilation into baryon-antibaryon pairs from spin-1/2 octet to spin-3/2 decuplet baryons. Our approach is based on perturbative QCD and treats baryons as quark-diquark systems. Using the same model parameters as in our previous work, supplemented by QCD sum-rule results for decuplet baryon wave functions, we are able to give absolute predictions for decuplet baryon cross sections without introducing new parameters. We find that the Δ++\Delta^{++} cross section is of the same order of magnitude as the proton cross section, well within experimental bounds.Comment: 14 pages, 2 figure

    String Theory and Water Waves

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    We uncover a remarkable role that an infinite hierarchy of non-linear differential equations plays in organizing and connecting certain {hat c}<1 string theories non-perturbatively. We are able to embed the type 0A and 0B (A,A) minimal string theories into this single framework. The string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy. We observe that there are several other string-like limits of the system, and conjecture that some of them are type IIA and IIB (A,D) minimal string backgrounds. We explain how these and several string-like special points arise and are connected. In some cases, the framework endows the theories with a non-perturbative definition for the first time. Notably, we discover that the Painleve IV equation plays a key role in organizing the string theory physics, joining its siblings, Painleve I and II, whose roles have previously been identified in this minimal string context.Comment: 49 pages, 4 figure
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