1,035 research outputs found
The Economic Incidence of R&D and Promotion Investments in the Australian Beef Industry
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
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
For the quintom models with arbitrary potential , 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
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
ΠΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΡ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ Π΄ΠΈΠ·Π΅Π»Ρ-ΠΏΠΎΠ΅Π·Π΄ΠΎΠ²
Π ΠΌΠΎΠ½ΠΎΠ³ΡΠ°ΡΠΈΠΈ ΠΈΠ·Π»ΠΎΠΆΠ΅Π½Ρ Π½Π°ΡΡΠ½ΡΠ΅ ΠΎΡΠ½ΠΎΠ²Ρ, ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ»ΠΎΠ³ΠΈΡ ΠΈ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ Π°ΠΊΡΡΠ°Π»ΡΠ½ΡΡ
Π·Π°Π΄Π°Ρ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈ ΠΎΠΏΡΠΈΠΌΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ Π΄ΠΈΠ·Π΅Π»Ρ-ΠΏΠΎΠ΅Π·Π΄ΠΎΠ² ΠΈ ΡΠ°Π·ΡΠ°Π±ΠΎΡΠΊΠΈ ΡΠΈΡΡΠ΅ΠΌΡ ΠΏΠΎΠ΄Π΄Π΅ΡΠΆΠΊΠΈ ΠΏΡΠΈΠ½ΡΡΠΈΡ ΡΠ΅ΡΠ΅Π½ΠΈΠΉ ΠΌΠ°ΡΠΈΠ½ΠΈΡΡΠΎΠΌ Π΄Π»Ρ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ Π΄Π²ΠΈΠΆΠ΅Π½ΠΈΠ΅ΠΌ Π΄ΠΈΠ·Π΅Π»Ρ-ΠΏΠΎΠ΅Π·Π΄Π° Ρ ΡΡΠ³ΠΎΠ²ΡΠΌ Π°ΡΠΈΠ½Ρ
ΡΠΎΠ½Π½ΡΠΌ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΎΠΌ. ΠΠ»Ρ Π½Π°ΡΡΠ½ΡΡ
ΠΈ ΠΈΠ½ΠΆΠ΅Π½Π΅ΡΠ½ΠΎ ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°Π±ΠΎΡΠ½ΠΈΠΊΠΎΠ², Π·Π°Π½ΠΈΠΌΠ°ΡΡΠΈΡ
ΡΡ ΠΏΡΠΎΠ΅ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΈ ΠΎΠ±ΡΠ»ΡΠΆΠΈΠ²Π°Π½ΠΈΠ΅ΠΌ ΡΡΠ³ΠΎΠ²ΠΎΠ³ΠΎ ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΠ³ΠΎ ΡΠΎΡΡΠ°Π²Π°, Π° ΡΠ°ΠΊΠΆΠ΅ ΡΠΏΠ΅ΡΠΈΠ°Π»ΠΈΡΡΠΎΠ² ΠΏΠΎ ΡΠ΅ΠΎΡΠΈΠΈ Π°Π²ΡΠΎΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΠΈ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΈΡΠΊΡΡΡΡΠ²Π΅Π½Π½ΡΡ
Π½Π΅ΠΉΡΠΎΠ½Π½ΡΡ
ΡΠ΅ΡΠ΅ΠΉ
Dark energy from conformal symmetry breaking
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
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
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
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
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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