29,384 research outputs found
Dry matter yields and quality of organic lupin/cereal mixtures for wholecrop forage
In view of climate change predictions and the general desirability of increasing the amount of home grown protein, a case exists for the investigation of lupins and lupin/cereal bicrop combinations as wholecrop forage on organic farms. A replicated randomised block trial is described which took place at the Royal Agricultural College, Cirencester, in 2005. This involved spring sown blue, white and yellow lupins, millet, wheat and triticale and lupin/cereal bi-crops. Data for dry matter yields for wholecrop silage, crude protein, MAD fi bre content and estimated ME, are presented for a single harvest. It is concluded that white lupins and white lupin bi-crops with spring wheat or triticale offer the best prospects for a viable wholecrop forage crop in an organic situation
ENVIRONMENTAL POLICY INFLUENCES ON LIVESTOCK STOCKING AND LOCATION DECISIONS
This paper explores the relationship between state level environmental regulations and stocking and location decisions in the U.S livestock and poultry industry (beef, chicken, dairy and hogs). Rather than conduct this analysis on a species-by-species basis, we choose to focus upon the overall size of the livestock industry (expressed in animal units) and the size of industry found on large, medium and small operations by state (48) and over time (28 yrs). Results indicate that industry may drive policy rather than the converse. However, since we also find that existing policy rules have differential impacts on the industry by operation size, we conclude that structural change in the industry may be driven in part by size or legal structure discriminating regulations.Demand and Price Analysis, Livestock Production/Industries,
An Appraisal of the Potential for Soybeans in the United Kingdom
Soybean is a most important crop worldwide, accounting for 56% of world oilseed production and 69% of world protein meal consumption in 2003 (Soystats, 2004). Since their introduction in the early 1800\u27s, forage soybeans have been grown widely in USA. Used originally as a forage crop, this use largely had been forgotten until Dr T. E. Devine (United States Department of Agriculture, Agricultural Research Service; USDA-ARS) released 4 new forage cultivars. Soybeans potentially offer UK farmers a high quality protein source in a short season and also meet the requirements of supermarket chains to remain GM free. This paper aims to indicate whether soybeans can be grown successfully in the UK
An Error-Components Three-Stage Least-Squares Model of Investment Allocation by Farm Households
This paper is an assessment of patterns of investment by farm households via an econometric model adapted from a land allocation approach of Holt (1999). This analysis will shed light on the importance of different classes of assets to farm household well-being, and show the reaction of farm households to a variety of market, international and government effects.Farm Management,
Ballistic transport is dissipative: the why and how
In the ballistic limit, the Landauer conductance steps of a mesoscopic
quantum wire have been explained by coherent and dissipationless transmission
of individual electrons across a one-dimensional barrier. This leaves untouched
the central issue of conduction: a quantum wire, albeit ballistic, has finite
resistance and so must dissipate energy. Exactly HOW does the quantum wire shed
its excess electrical energy? We show that the answer is provided, uniquely, by
many-body quantum kinetics. Not only does this inevitably lead to universal
quantization of the conductance, in spite of dissipation; it fully resolves a
baffling experimental result in quantum-point-contact noise. The underlying
physics rests crucially upon the action of the conservation laws in these open
metallic systems.Comment: Invited Viewpoint articl
Radiation from perfect mirrors starting from rest and the black body spectrum
We address the question of radiation emission from a perfect mirror that
starts from rest and follows the trajectory z=-ln(cosht) till t->Infinity. We
show that a correct derivation of the black body spectrum via the calculation
of the Bogolubov amplitudes requires consideration of the whole trajectory and
not just of its asymptotic part.Comment: Typos correcte
From spinning to non-spinning cosmic string spacetimes
We analyse the properties of a fluid generating a spinning cosmic string
spacetime with flat limiting cases corresponding to a constant angular momentum
in the infinite past and static configuration in the infinite future. The
spontaneous loss of angular momentum of a spinning cosmic string due to
particle emission is discussed. The rate of particle production between the
spinning and non-spinning cosmic string spacetimes is calculated.Comment: 11 pages, 1 figure, LaTeX To appear in Class. Quantum Gra
Spontaneous excitation of an accelerated atom: The contributions of vacuum fluctuations and radiation reaction
We consider an atom in interaction with a massless scalar quantum field. We
discuss the structure of the rate of variation of the atomic energy for an
arbitrary stationary motion of the atom through the quantum vacuum. Our main
intention is to identify and to analyze quantitatively the distinct
contributions of vacuum fluctuations and radiation reaction to the spontaneous
excitation of a uniformly accelerated atom in its ground state. This gives an
understanding of the role of the different physical processes underlying the
Unruh effect. The atom's evolution into equilibrium and the Einstein
coefficients for spontaneous excitation and spontaneous emission are
calculated.Comment: 13 pages, KONS-RGKU-94-09, to appear in Phys. Rev.
Vanishing Hawking Radiation from a Uniformly Accelerated Black Hole
We consider quantum fields around uniformly accelerated black holes. At a
particular value of the acceleration, the Bogolubov transformation which would
be responsible for the late-time Hawking radiation, is found to be trivial.
When this happens, Hawking's thermal radiation, Doppler-shifted or not, is
absent to the asymptotic inertial observers despite the nonzero Hawking
temperature, while the co-moving observers find the black hole radiance exactly
balanced by the acceleration heat bath. After a brief comparison to the
classical system of a uniformly accelerated charge, we close with two important
comments. (Phys. Rev. Lett. 75 (1995) 382)Comment: LaTeX, 10pages, 2 figures (a typo in Eq.(3) corrected; minor
revisions to accomodate the length limitation of the journal
Robustness of adiabatic quantum computation
We study the fault tolerance of quantum computation by adiabatic evolution, a
quantum algorithm for solving various combinatorial search problems. We
describe an inherent robustness of adiabatic computation against two kinds of
errors, unitary control errors and decoherence, and we study this robustness
using numerical simulations of the algorithm.Comment: 11 pages, 5 figures, REVTe
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