2,900 research outputs found

    Prices and volumes of options: A simple theory of risk sharing when markets are incomplete

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    We present a simple theory of business-cycle movements of option prices and volumes. This theory relies on time-varying heterogeneity between agents in their demand for insurance against aggregate risk. Formally, we build an infinite-horizon model where agents face an aggregate risk, but also different levels of idiosyncratic risk. We manage to characterize analytically a general equilibrium in which positive quantities of derivatives are traded. This allows us to explain the informational content of derivative volumes over the business cycle. We also carry out welfare analysis with respect to the introduction of options, which appears not to be Pareto-improving.Option Pricing, Open Interest, Incomplete Markets.

    Incomplete markets, liquidation risk, and the term structure of interest rates

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    We analyze the term structure of real interest rates in a general equilibrium model with incomplete markets and borrowing constraints. Agents are subject to both aggregate and idiosyncratic income shocks, which latter may force them into early portfolio liquidation in a bad aggregate state. We derive a closed-form equilibrium with limited agent heterogeneity (despite market incompleteness), which allows us to produce analytical expressions for bond prices and returns at any maturity. The attractiveness of bonds as liquidity makes aggregate bond demand downward-sloping, so that greater bond supply raises both the level and the slope of the yield curve. Moreover, time-variations in liquidation risk are shown to help explain the rejection of the Expectations Hypothesis.Incomplete markets; yield curve; borrowing constraints.

    Use of Ecogeographical Factors for Sampling a Core Collection of Perennial Ryegrass

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    In order to set up a core collection of wild populations of pei:ennial ryegra11 {Lolium perenne L.), 3 different criteria have been combined lo make a choice of populations: similarities between populations, geographic location and ecological characteristics of their original sites. Different multivariate analysis and clustering methods, introducing a geographic contiguity CXJnstnint were used to sample, among a set of 550 Prench wild populations, 114 populations 111 representative as po11ible of the whole variability

    The preparation of 1, 1\u27tetramethylene ferrocene

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    The discovery of ferrocene, bis-cyclopentadienyl iron, in 1951 stimulated further research into a relatively new field of Organic Chemistry, organometallies. Ferrocene is the first of a series of transition metal-organic ring compounds in which the metallic atom is bound covalently to two cyclopentadiene rings (Fig III). The rings are superimposed over one another with the single atom inbetween; thus, they are often referred to as “sandwich compounds.” The following procedure is that which Rinehart (11) used to prepare the acid derivative ÎČ-ferrocenoylpropionic acid (VII). The preparation consists of adding 7.4 g. of ferrocene and 2.0 g. of succinic anhydride in 150 ml. of methylene chloride to 5.8 g. of aluminum chloride in 150 ml. of methylene chloride. The reaction was stirred for two hours at room temperature, then decanted over ice. The crude acid was extracted from methylene chloride with sodium carbonate, filtered through Celite, and reprecipitated with dilute hydrochloric acid. The orange acid was recrystallized from methanol-bensene. Results of elemental analysis for carbon, hydrogen, and iron, and infra-red data supported the proposed structure (VIII)

    Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

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    Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved questions in galactic astronomy. However, theoretical works are proposing new testable predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this letter we analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D chemical composition and Hα\alpha line-of-sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially-slower, radially-outward (tangentially-faster, radially-inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behaviour in a NN-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September 2

    A simulation system for behaviour evaluation of off-rooad mobile robots

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    Abstract: This study deals with optimization of planetary rover traversability over challenging outdoor terrains. In this aim, it is necessary to simulate rover behaviour on soft soil with a high degree of realism. The paper describes a simulation system for mobile robots evolving on natural and unstructured surfaces. This simulator integrates the whole dynamics of the multibody systems and complex interactions with soft ground as well as control schemes.
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