3,013 research outputs found
Weight function for the quantum affine algebra
We give a precise expression for the universal weight function of the quantum
affine algebra . The calculations use the technique of
projecting products of Drinfeld currents on the intersections of Borel
subalgebras.Comment: 28 page
Fast ignition driven by quasi-monoenergetic ions: Optimal ion type and reduction of ignition energies with an ion beam array
Fast ignition of inertial fusion targets driven by quasi-monoenergetic ion
beams is investigated by means of numerical simulations. Light and intermediate
ions such as lithium, carbon, aluminium and vanadium have been considered.
Simulations show that the minimum ignition energies of an ideal configuration
of compressed Deuterium-Tritium are almost independent on the ion atomic
number. However, they are obtained for increasing ion energies, which scale,
approximately, as Z^2, where Z is the ion atomic number. Assuming that the ion
beam can be focused into 10 {\mu}m spots, a new irradiation scheme is proposed
to reduce the ignition energies. The combination of intermediate Z ions, such
as 5.5 GeV vanadium, and the new irradiation scheme allows a reduction of the
number of ions required for ignition by, roughly, three orders of magnitude
when compared with the standard proton fast ignition scheme
Communication Enhancement Through Quantum Coherent Control of Channels in an Indefinite Causal-order Scenario
In quantum Shannon theory, transmission of information is enhanced by quantum
features. Up to very recently, the trajectories of transmission remained fully
classical. Recently, a new paradigm was proposed by playing quantum tricks on
two completely depolarizing quantum channels i.e. using coherent control in
space or time of the two quantum channels. We extend here this control to the
transmission of information through a network of an arbitrary number of
channels with arbitrary individual capacity i.e. information preservation
characteristics in the case of indefinite causal order. We propose a formalism
to assess information transmission in the most general case of channels in
an indefinite causal order scenario yielding the output of such transmission.
Then we explicitly derive the quantum switch output and the associated Holevo
limit of the information transmission for , as a function of all
involved parameters. We find in the case that the transmission of
information for three channels is twice of transmission of the two channel case
when a full superposition of all possible causal orders is used
Noncanonical Quantization of Gravity. I. Foundations of Affine Quantum Gravity
The nature of the classical canonical phase-space variables for gravity
suggests that the associated quantum field operators should obey affine
commutation relations rather than canonical commutation relations. Prior to the
introduction of constraints, a primary kinematical representation is derived in
the form of a reproducing kernel and its associated reproducing kernel Hilbert
space. Constraints are introduced following the projection operator method
which involves no gauge fixing, no complicated moduli space, nor any auxiliary
fields. The result, which is only qualitatively sketched in the present paper,
involves another reproducing kernel with which inner products are defined for
the physical Hilbert space and which is obtained through a reduction of the
original reproducing kernel. Several of the steps involved in this general
analysis are illustrated by means of analogous steps applied to one-dimensional
quantum mechanical models. These toy models help in motivating and
understanding the analysis in the case of gravity.Comment: minor changes, LaTeX, 37 pages, no figure
On dynamical adjoint functor
We give an explicit formula relating the dynamical adjoint functor and
dynamical twist over nonalbelian base to the invariant pairing on parabolic
Verma modules. As an illustration, we give explicit - and
-invariant star product on projective spaces
Gastrointestinal tract size, total-tract digestibility, and rumen microflora in different dairy cow genotypes
peer-reviewedThe superior milk production efficiency of Jersey (JE) and Jersey Ă— Holstein-Friesian (JE Ă— HF) cows compared with Holstein-Friesian (HF) has been widely published. The biological differences among dairy cow genotypes, which could contribute to the milk production efficiency differences, have not been as widely studied however. A series of component studies were conducted using cows sourced from a longer-term genotype comparison study (JE, JE Ă— HF, and HF). The objectives were to (1) determine if differences exist among genotypes regarding gastrointestinal tract (GIT) weight, (2) assess and quantify whether the genotypes tested differ in their ability to digest perennial ryegrass, and (3) examine the relative abundance of specific rumen microbial populations potentially relating to feed digestibility. Over 3 yr, the GIT weight was obtained from 33 HF, 35 JE, and 27 JE Ă— HF nonlactating cows postslaughter. During the dry period the cows were offered a perennial ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF than for JE and JE Ă— HF. When expressed as a proportion of body weight (BW), JE and JE Ă— HF had a heavier GIT weight than HF. In vivo digestibility was evaluated on 16 each of JE, JE Ă— HF, and HF lactating dairy cows. Cows were individually stalled, allowing for the total collection of feces and were offered freshly cut grass twice daily. During this time, daily milk yield, BW, and dry matter intake (DMI) were greater for HF and JE Ă— HF than for JE; milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ among the 3 genotypes. Intake capacity, expressed as DMI per BW, tended to be different among treatments, with JE having the greatest DMI per BW, HF the lowest, and JE Ă— HF being intermediate. Production efficiency, expressed as milk solids per DMI, was higher for JE than HF and JE Ă— HF. Digestive efficiency, expressed as digestibility of dry matter, organic matter, N, neutral detergent fiber, and acid detergent fiber, was higher for JE than HF. In grazing cows (n = 15 per genotype) samples of rumen fluid, collected using a transesophageal sampling device, were analyzed to determine the relative abundance of rumen microbial populations of cellulolytic bacteria, protozoa, and fungi. These are critically important for fermentation of feed into short-chain fatty acids. A decrease was observed in the relative abundance of Ruminococcus flavefaciens in the JE rumen compared with HF and JE Ă— HF. We can deduce from this study that the JE genotype has greater digestibility and a different rumen microbial population than HF. Jersey and JE Ă— HF cows had a proportionally greater GIT weight than HF. These differences are likely to contribute to the production efficiency differences among genotypes previously reported
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