3,799 research outputs found

    New Bathonian (Middle Jurassic) sauropod remains from the Valtos Formation, Isle of Skye, Scotland

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    The discovery of a sauropod tooth and a single sauropod footprint from the Valtos Formation supplements our knowledge of these dinosaurs from the Middle Jurassic of the Isle of Skye. Although the family cannot be determined from this single tooth, it is thought that it represents a primitive eusauropod and may belong to a similar sauropod to that previously described from limited isolated osteological evidence (caudal vertebra, damaged humerus and a rib). The characteristics that suggest this affinity include evidence of denticles on one edge of the tooth, wrinkling and granulation of the enamel, wear suggesting crown-to-crown occlusion, and the spatulate tooth shape. The single sauropod footprint is the oldest record of a sauropod footprint from the Middle Jurassic of Skye

    Liquidity In Commercial Property Markets: Deconstructing The Transaction Process

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    This paper draws from a wider research programme in the UK undertaken for the Investment Property Forum examining liquidity in commercial property. One aspect of liquidity is the process by which transactions occur including both how properties are selected for sale and the time taken to transact. The paper analyses data from three organisations; a property company, a major financial institution and an asset management company, formally a major public sector pension fund. The data covers three market states and includes sales completed in 1995, 2000 and 2002 in the UK. The research interviewed key individuals within the three organisations to identify any common patterns of activity within the sale process and also identified the timing of 187 actual transactions from inception of the sale to completion. The research developed a taxonomy of the transaction process. Interviews with vendors indicated that decisions to sell were a product of a combination of portfolio, specific property and market based issues. Properties were generally not kept in a “readiness for sale” state. The average time from first decision to sell the actual property to completion had a mean time of 298 days and a median of 190 days. It is concluded that this study may underestimate the true length of the time to transact for two reasons. Firstly, the pre-marketing period is rarely recorded in transaction files. Secondly, and more fundamentally, studies of sold properties may contain selection bias. The research indicated that vendors tended to sell properties which it was perceived could be sold at a ‘fair’ price in a reasonable period of time.

    Ambipolar diffusion in low-mass star formation. I. General comparison with the ideal MHD case

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    In this paper, we provide a more accurate description of the evolution of the magnetic flux redistribution during prestellar core collapse by including resistive terms in the magnetohydrodynamics (MHD) equations. We focus more particularly on the impact of ambipolar diffusion. We use the adaptive mesh refinement code RAMSES to carry out such calculations. The resistivities required to calculate the ambipolar diffusion terms were computed using a reduced chemical network of charged, neutral and grain species. The inclusion of ambipolar diffusion leads to the formation of a magnetic diffusion barrier in the vicinity of the core, preventing accumulation of magnetic flux in and around the core and amplification of the field above 0.1G. The mass and radius of the first Larson core remain similar between ideal and non-ideal MHD models. This diffusion plateau has crucial consequences on magnetic braking processes, allowing the formation of disk structures. Magnetically supported outflows launched in ideal MHD models are weakened when using non-ideal MHD. Contrary to ideal MHD misalignment between the initial rotation axis and the magnetic field direction does not significantly affect the results for a given mu, showing that the physical dissipation truly dominate over numerical diffusion. We demonstrate severe limits of the ideal MHD formalism, which yield unphysical behaviours in the long-term evolution of the system. This includes counter rotation inside the outflow, interchange instabilities, and flux redistribution triggered by numerical diffusion, none observed in non-ideal MHD. Disks with Keplerian velocity profiles form in all our non-ideal MHD simulations, with final mass and size which depend on the initial magnetisation. This ranges from a few 0.01 solar masses and 20-30 au for the most magnetised case (mu=2) to 0.2 solar masses and 40-80 au for a lower magnetisation (mu=5).Comment: Accepted in A&A section 7 (on Wednesday, september the 16th, year 2015

    Structure-Activity Relationships in Glucosinolates as Oviposition Stimulants of the Cabbage Root Fly, Delia radicum (L.)

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    A statistically sound and quantifiable bioassay procedure was developed for determining the response of adult Delia radicum to oviposition stimulants. The method was based on the use of surrogate leaves coated with test compounds. All of the test compounds were of purity 99% or greater. Twelve of the tested compounds were synthesised the remaining twenty four were either donated or available commercially. Attempts to follow literature methods to synthesise glucosinolates were unsatisfactory and an investigation of the procedures led to a number of synthetic modifications. Despite various attempts, the failure to sulphate a thiohydroximate to produce a glucosinolate was not resolved. Attempts to correlate oviposition stimulus with chemical structure produced a very significant finding. The results showed that a wide variety of chemically dissimilar compounds were effective stimulants providing they contained an S=O group. Thus sulphoxides, sulphones, sulphinic, sulphonic acids and their derivatives were all effective. Thiols and thioethers were non-stimulant, as were naturally occurring glucosinolates which had been chemically modified by the removal of the oxime sulphate group. The relative effectiveness of the oviposition stimulants was examined by determining the number of eggs laid on surrogate leaves relative to a prop-2-enylglucosinolate (sinigrin) standard over a range or concentrations. Statistical modelling of the data collected produced a maximum relative number of eggs laid (YMAX) at an optimum concentration (C) for each compound. It was not found possible to produce a single parameter combining YMAX and C, neither did any other structure-activity feature emerge from the study.W H Knights & Son Ltd, Crow Hall Farm, Gooderstone, Kings Lynn, Norfolk. PE33 9D
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