1,035 research outputs found

    The Economic Incidence of R&D and Promotion Investments in the Australian Beef Industry

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    The issue of the relative returns to farmers from R&D and promotion is examined using a multi-sectoral equilibrium displacement model of the Australian beef industry. Total economic surplus changes and their distributions among various industry groups resulting from 1% cost reductions in various farm and off-farm sectors, and from 1% price premiums from domestic and export market promotion, are estimated. The results are consistent with previous studies in showing that in general, the share of total benefits to farmers is larger from on-farm research than from most off-farm research, and is larger from most types of research than from domestic promotion. The share of total benefits to farmers is larger from export promotion than from off-farm research, and from domestic promotion. The net returns from the different cost-reduction or demand-enhancing scenarios depend on the costs of achieving them.Economics of R&D, promotion, beef industry, equilibrium displacement modelling.

    Zener transitions between dissipative Bloch bands. II: Current Response at Finite Temperature

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    We extend, to include the effects of finite temperature, our earlier study of the interband dynamics of electrons with Markoffian dephasing under the influence of uniform static electric fields. We use a simple two-band tight-binding model and study the electric current response as a function of field strength and the model parameters. In addition to the Esaki-Tsu peak, near where the Bloch frequency equals the damping rate, we find current peaks near the Zener resonances, at equally spaced values of the inverse electric field. These become more prominenent and numerous with increasing bandwidth (in units of the temperature, with other parameters fixed). As expected, they broaden with increasing damping (dephasing).Comment: 5 pages, LateX, plus 5 postscript figure

    Asymptotic behavior of w in general quintom model

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    For the quintom models with arbitrary potential V=V(Ο•,Οƒ)V=V(\phi,\sigma), the asymptotic value of equation of state parameter w is obtained by a new method. In this method, w of stable attractors are calculated by using the ratio (d ln V)/(d ln a) in asymptotic region. All the known results, have been obtained by other methods, are reproduced by this method as specific examples.Comment: 8 pages, one example is added, accepted for publication in Gen. Rel. Gra

    Cosmological models with linearly varying deceleration parameter

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    We propose a new law for the deceleration parameter that varies linearly with time and covers Berman's law where it is constant. Our law not only allows one to generalize many exact solutions that were obtained assuming constant deceleration parameter, but also gives a better fit with data (from SNIa, BAO and CMB), particularly concerning the late time behavior of the universe. According to our law only the spatially closed and flat universes are allowed; in both cases the cosmological fluid we obtain exhibits quintom like behavior and the universe ends with a big-rip. This is a result consistent with recent cosmological observations.Comment: 12 pages, 7 figures; some typo corrections; to appear in International Journal of Theoretical Physic

    ΠœΠΎΠ΄Π΅Π»ΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈ оптимизация процСссов управлСния Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ дизСль-ΠΏΠΎΠ΅Π·Π΄ΠΎΠ²

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    Π’ ΠΌΠΎΠ½ΠΎΠ³Ρ€Π°Ρ„ΠΈΠΈ ΠΈΠ·Π»ΠΎΠΆΠ΅Π½Ρ‹ Π½Π°ΡƒΡ‡Π½Ρ‹Π΅ основы, мСтодология ΠΈ Ρ€Π΅Π·ΡƒΠ»ΡŒΡ‚Π°Ρ‚Ρ‹ практичСского Ρ€Π΅ΡˆΠ΅Π½ΠΈΡ Π°ΠΊΡ‚ΡƒΠ°Π»ΡŒΠ½Ρ‹Ρ… Π·Π°Π΄Π°Ρ‡ модСлирования ΠΈ ΠΎΠΏΡ‚ΠΈΠΌΠΈΠ·Π°Ρ†ΠΈΠΈ процСссов управлСния Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ дизСль-ΠΏΠΎΠ΅Π·Π΄ΠΎΠ² ΠΈ Ρ€Π°Π·Ρ€Π°Π±ΠΎΡ‚ΠΊΠΈ систСмы ΠΏΠΎΠ΄Π΄Π΅Ρ€ΠΆΠΊΠΈ принятия Ρ€Π΅ΡˆΠ΅Π½ΠΈΠΉ ΠΌΠ°ΡˆΠΈΠ½ΠΈΡΡ‚ΠΎΠΌ для Π°Π²Ρ‚ΠΎΠΌΠ°Ρ‚ΠΈΠ·Π°Ρ†ΠΈΠΈ процСссов управлСния Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ дизСль-ΠΏΠΎΠ΅Π·Π΄Π° с тяговым асинхронным ΠΏΡ€ΠΈΠ²ΠΎΠ΄ΠΎΠΌ. Для Π½Π°ΡƒΡ‡Π½Ρ‹Ρ… ΠΈ ΠΈΠ½ΠΆΠ΅Π½Π΅Ρ€Π½ΠΎ тСхничСских Ρ€Π°Π±ΠΎΡ‚Π½ΠΈΠΊΠΎΠ², Π·Π°Π½ΠΈΠΌΠ°ΡŽΡ‰ΠΈΡ…ΡΡ ΠΏΡ€ΠΎΠ΅ΠΊΡ‚ΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΈ обслуТиваниСм тягового ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΠ³ΠΎ состава, Π° Ρ‚Π°ΠΊΠΆΠ΅ спСциалистов ΠΏΠΎ Ρ‚Π΅ΠΎΡ€ΠΈΠΈ автоматичСского управлСния ΠΈ ΠΏΡ€ΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡŽ искусствСнных Π½Π΅ΠΉΡ€ΠΎΠ½Π½Ρ‹Ρ… сСтСй

    Dark energy from conformal symmetry breaking

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    The breakdown of conformal symmetry in a conformally invariant scalar-tensor gravitational model is revisited in the cosmological context. Although the old scenario of conformal symmetry breaking in cosmology containing scalar field has already been used in many earlier works, it seems that no special attention has been paid for the investigation on the possible connection between the breakdown of conformal symmetry and the existence of dark energy. In this paper, it is shown that the old scenario of conformal symmetry breaking in cosmology, if properly interpreted, not only has a potential ability to describe the origin of dark energy as a symmetry breaking effect, but also may resolve the coincidence problem.Comment: 11 pages, minor revision, published online in EPJ

    An Asymmetric Cone Model for Halo Coronal Mass Ejections

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    Due to projection effects, coronagraphic observations cannot uniquely determine parameters relevant to the geoeffectiveness of CMEs, such as the true propagation speed, width, or source location. The Cone Model for Coronal Mass Ejections (CMEs) has been studied in this respect and it could be used to obtain these parameters. There are evidences that some CMEs initiate from a flux-rope topology. It seems that these CMEs should be elongated along the flux-rope axis and the cross section of the cone base should be rather elliptical than circular. In the present paper we applied an asymmetric cone model to get the real space parameters of frontsided halo CMEs (HCMEs) recorded by SOHO/LASCO coronagraphs in 2002. The cone model parameters are generated through a fitting procedure to the projected speeds measured at different position angles on the plane of the sky. We consider models with the apex of the cone located at the center and surface of the Sun. The results are compared to the standard symmetric cone model

    Dynamics of the self-interacting chameleon cosmology

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    In this article we study the properties of the flat FRW chameleon cosmology in which the cosmic expansion of the Universe is affected by the chameleon field and dark energy. In particular, we perform a detailed examination of the model in the light of numerical analysis. The results illustrate that the interacting chameleon filed plays an important role in late time universe acceleration and phantom crossing.Comment: 13 pages, 8 figures, to appear in Astrophysics and Space Sc

    Interacting Three Fluid System and Thermodynamics of the Universe Bounded by the Event Horizon

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    The work deals with the thermodynamics of the universe bounded by the event horizon. The matter in the universe has three constituents namely dark energy, dark matter and radiation in nature and interaction between then is assumed. The variation of entropy of the surface of the horizon is obtained from unified first law while matter entropy variation is calculated from the Gibbss' law. Finally, validity of the generalized second law of thermodynamics is examined and conclusions are written point wise.Comment: 7 page

    Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon

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    In standard cosmology, with the evolution of the universe, the matter density and thermodynamic pressure gradually decreases. Also in course of evolution, the matter in the universe obeys (or violates) some restrictions or energy conditions. If the matter distribution obeys strong energy condition (SEC), the universe is in a decelerating phase while violation of SEC indicates an accelerated expansion of the universe. In the period of accelerated expansion the matter may be either of quintessence nature or of phantom nature depending on the fulfilment of the weak energy condition (WEC) or violation of it. As recent observational evidences demand that the universe is going through an accelerated expansion so mater should be either quintessence or phantom in nature. In the present work we study the evolution of the universe through the phantom barrier (i.e. the dividing line between the quintessence and phantom era) and examine how apparent and event horizon change across the barrier. Finally, we investigate the possibility of occurrence of any singularity in phantom era.Comment: 7 pages and 4 figure
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