50,330 research outputs found

    Commodity Markets: Rational Expectations in Markets With Irrational Investors

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    The "financialization" of commodity markets have become a concern for policy makers and market participants. What was once a market for the hedging of holding physical commodities has expanded to become a market for the diversification of financial assets. When financial assets diversification goals are decoupled from the fundamental factors that affect producers and consumers of physical goods futures markets may not be as efficient in aggregating information concerning the economics of the underlying commodity. Theoretical understanding of whether commodity futures market function well under exogenous shifts in demand for futures contracts depend on our assumptions of how market participants behave, including their level of risk aversion. This paper builds a competitive storage model with an explicit futures market that incorporates irrational shocks to demand for futures contracts. This model is flexible enough to investigate the impact of the "financialization" of commodity futures markets and the resulting impacts.commodity, futures, financialization, competitive storage, rational expectations, Agricultural and Food Policy, Agricultural Finance, Financial Economics, Risk and Uncertainty,

    A meta-narrative review of electronic patient records

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    This session comprises four papers that consider how systematic review methods may be developed in order to make the best use of complex evidence in education and health. The methods and approaches reflected upon in these papers are not drawn from a single research tradition, but share a common goal of broadening the methodological scope of systematic reviews and better understanding the utilisation of knowledge produced in this way. The first paper (Henry Potts) reports an ongoing review using a meta-narrative approach to make sense of the diverse sources of knowledge regarding electronic patient records. The review method has stressed the importance of understanding knowledge from within the research tradition in which it was produced; it is argued that this has important implications for the way that evidence is utilised in the policy making process. The second paper (Geoff Wong) reflects upon the experience of using an explicit realist approach in the synthesis of the evidence in Internet based learning. This realist synthesis offers a method of making sense of the highly heterogeneous and context dependent evidence which exists in this field thus enabling greater insights into what makes such educational interventions ‘work’. The third paper (Rod Sheaff) reports a review of the predominantly qualitative research literature on organisational structures and their impacts upon policy outcomes in health systems. A scoping study found 14389 relevant papers of which 1568 were selected for review. These studies were very variable in the amount and quality of the qualitative data, hence 'evidence', which they reported. The paper describes an attempt to adapt realist methods so as to synthesise such bodies of research in ways which take account of this variation in the strength of qualitative evidence. The fourth paper (Mark Pearson) draws upon the work of Donald Campbell and colleagues in order to gain a fuller understanding of how systematic reviews are utilised in the policy making process. It is argued that interpretive approaches to understanding policy making (such as rhetorical analysis) need to be tempered with a more nuanced understanding of research validity. The case is made that interpretive approaches not only can, but should, be melded with research validity to increase understanding of the policy making process

    Analysis of pion elliptic flows and HBT interferometry in a granular quark-gluon plasma droplet model

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    In many simulations of high-energy heavy-ion collisions on an event-by-event analysis, it is known that the initial energy density distribution in the transverse plane is highly fluctuating. Subsequent longitudinal expansion will lead to many longitudinal tubes of quark-gluon plasma which have tendencies to break up into many spherical droplets because of sausage instabilities. We are therefore motivated to use a model of quark-gluon plasma granular droplets that evolve hydrodynamically to investigate pion elliptic flows and Hanbury-Brown-Twiss interferometry. We find that the data of pion transverse momentum spectra, elliptic flows, and HBT radii in \sqrt{s_{NN}}=200 GeV Au + Au collisions at RHIC can be described well by an expanding source of granular droplets with an anisotropic velocity distribution.Comment: 9 pages, 6 figures, in Late

    Heavy flavor kinetics at the hadronization transition

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    We investigate the in-medium modification of the charmonium breakup processes due to the Mott effect for light (pi, rho) and open-charm (D, D*) quark-antiquark bound states at the chiral/deconfinement phase transition. The Mott effect for the D-mesons effectively reduces the threshold for charmonium breakup cross sections, which is suggested as an explanation of the anomalous J/psi suppression phenomenon in the NA50 experiment. Further implications of finite-temperature mesonic correlations for the hadronization of heavy flavors in heavy-ion collisions are discussed.Comment: 4 pages, 2 figures, Contribution to SQM2001 Conference, submitted to J. Phys.

    Electroproduction of the d* dibaryon

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    The unpolarized cross section for the electroproduction of the isoscalar Jπ=3+J^\pi = 3^+ di-delta dibaryon d∗d^* is calculated for deuteron target using a simple picture of elastic electron-baryon scattering from the ΔΔ(7D1)\Delta \Delta (^7D_1) and the NN(3S1)NN (^3S_1) components of the deuteron. The calculated differential cross section at the electron lab energy of 1 GeV has the value of about 0.24 (0.05) nb/sr at the lab angle of 10∘^\circ (30∘^\circ) for the Bonn B potential when the dibaryon mass is taken to be 2.1 GeV. The cross section decreases rapidly with increasing dibaryon mass. A large calculated width of 40 MeV for d∗(ΔΔ7S3)d^*(\Delta\Delta ^7S_3) combined with a small experimental upper bound of 0.08 MeV for the d∗d^* decay width appears to have excluded any low-mass d∗d^* model containing a significant admixture of the ΔΔ(7S3)\Delta\Delta (^7S_3) configuration.Comment: 11 journal-style pages, 8 figure

    Non-equilibrium chemistry and dust formation in AGB stars as probed by SiO line emission

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    We have performed high spatial resolution observations of SiO line emission for a sample of 11 AGB stars using the ATCA, VLA and SMA interferometers. Detailed radiative transfer modelling suggests that there are steep chemical gradients of SiO in their circumstellar envelopes. The emerging picture is one where the radial SiO abundance distribution starts at an initial high abundance, in the case of M-stars consistent with LTE chemistry, that drastically decreases at a radius of ~1E15 cm. This is consistent with a scenario where SiO freezes out onto dust grains. The region of the wind with low abundance is much more extended, typically ~1E16 cm, and limited by photodissociation. The surpisingly high SiO abundances found in carbon stars requires non-equilibrium chemical processes.Comment: 2 pages, 1 figure. To be published in the proceedings of the conference "Why Galaxies Care about AGB Stars", held in Vienna, August 7-11, 2006; F. Kerschbaum, C. Charbonnel, B. Wing eds, ASP Conf.Ser. in pres

    Revealing the Archetype: The Journey of a Trecento Madonna and Child at the National Museum of Scotland

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    The National Museums Scotland Madonna and Child project sought to uncover and document the history of a fine polychrome wood carving attributed to The Master of the Gualino St Catherine and to prepare it for display. A new body of knowledge has been assembled by the interdisciplinary team. The conservation treatment was informed by this work and led to further discoveries: the removal of overpaint exposing a previously hidden underdrawing. The ethics of the treatment decisions, including the removal of the Christ Child’s 1960s’ fingers required team dialogue and was opened up for the public to respond to in a series of blogs. The discovery of a rich polychromy including gold and glazed tin has led to further plans to produce a 3-D colour reconstruction. The collaborations developed during this project will facilitate future joint ventures for polychrome sculpture in Scottish collections
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