11,905 research outputs found
A New Recursion Relation for the 6j-Symbol
The 6j-symbol is a fundamental object from the re-coupling theory of SU(2)
representations. In the limit of large angular momenta, its asymptotics is
known to be described by the geometry of a tetrahedron with quantized lengths.
This article presents a new recursion formula for the square of the 6j-symbol.
In the asymptotic regime, the new recursion is shown to characterize the
closure of the relevant tetrahedron. Since the 6j-symbol is the basic building
block of the Ponzano-Regge model for pure three-dimensional quantum gravity, we
also discuss how to generalize the method to derive more general recursion
relations on the full amplitudes.Comment: 10 pages, v2: title and introduction changed, paper re-structured;
Annales Henri Poincare (2011
Manifestation of three-body forces in f7/2-shell nuclei
The traditional nuclear shell model approach is extended to include many-body
forces. The empirical Hamiltonian with a three-body force is constructed for
the identical nucleons on the 0f7/2 shell. Manifestations of the three-body
force in spectra, binding energies, seniority mixing, particle-hole symmetry,
electromagnetic and particle transition rates are investigated. It is shown
that in addition to the usual expansion of the valence space within the
tranditional two-body shell model, the three-body component in the Hamiltonian
can be an important part improving the quality of the theoretical approach.Comment: 5 pages, 1 figur
Finite element approximation of a phase field model for void electromigration
We consider a fully practical finite element approximation of the nonlinear degenerate parabolic syste
The Dextrose, Levulose, Sucrose, and Acid Content of the Juice from 39 Grape Clones
The dextrose, levulose, sucrose and acid contents of the juice from 39 grape clones were determined to obtain information for use in breeding improved varieties. The 39 clones represented a survey of Vitis comprising native American species, American-type, French hybrid, and vinifera varieties.
Wide variation existed in the percentages of each sugar, in pH, titratable acidity, and buffer systems.
Sucrose was present in significant amounts only in clones which were derivatives of V. labrusa.
The levulose-dextrose ratio varied from 0.81 to 1.49; in only one clone was it less than 1.00.
The per cent of acid ranged from 0.35 to 4.74; the pH from 2.69 to 4.05.
The desirability of the standardization of sampling, extraction, and analytical methods in order that valid comparisons may be made between the results of various investigations is pointed out.
Certain aspects of the potential use of the information from these data in the development of improved grape varieties is presented
Critical dynamics of diluted relaxational models coupled to a conserved density (diluted model C)
We consider the influence of quenched disorder on the relaxational critical
dynamics of a system characterized by a non-conserved order parameter coupled
to the diffusive dynamics of a conserved scalar density (model C). Disorder
leads to model A critical dynamics in the asymptotics, however it is the
effective critical behavior which is often observed in experiments and in
computer simulations and this is described by the full set of dynamical
equations of diluted model C. Indeed different scenarios of effective critical
behavior are predicted.Comment: 4 pages, 5 figure
Somatostatin agonist pasireotide inhibits exercise stimulated growth in the male Siberian hamster (Phodopus sungorus)
R.Dumbell was supported by a University of Aberdeen PhD studentship and a research visit grant awarded by the British Society of Neuroendocrinology. Further support was provided by the Scottish Government Rural and Environment Science and Analytical Services Division (Barrett and the German Research Foundation (DFG; STE 331/8-1; Steinlechner lab). We are grateful for technical assistance from Dana Wilson at RINH and Siegried Hiliken at UVMH, and thank Dr Claus-Dieter Mayer of Biomathematics & Statistics Scotland for valuable advice on statistical analysis.Peer reviewedPostprin
Band Mapping in One-Step Photoemission Theory: Multi-Bloch-Wave Structure of Final States and Interference Effects
A novel Bloch-waves based one-step theory of photoemission is developed
within the augmented plane wave formalism. Implications of multi-Bloch-wave
structure of photoelectron final states for band mapping are established.
Interference between Bloch components of initial and final states leads to
prominent spectral features with characteristic frequency dispersion
experimentally observed in VSe_2 and TiTe_2. Interference effects together with
a non-free-electron nature of final states strongly limit the applicability of
the common direct transitions band mapping approach, making the tool of
one-step analysis indispensable.Comment: 4 jpg figure
Spin Foam Models of Matter Coupled to Gravity
We construct a class of spin foam models describing matter coupled to
gravity, such that the gravitational sector is described by the unitary
irreducible representations of the appropriate symmetry group, while the matter
sector is described by the finite-dimensional irreducible representations of
that group. The corresponding spin foam amplitudes in the four-dimensional
gravity case are expressed in terms of the spin network amplitudes for
pentagrams with additional external and internal matter edges. We also give a
quantum field theory formulation of the model, where the matter degrees of
freedom are described by spin network fields carrying the indices from the
appropriate group representation. In the non-topological Lorentzian gravity
case, we argue that the matter representations should be appropriate SO(3) or
SO(2) representations contained in a given Lorentz matter representation,
depending on whether one wants to describe a massive or a massless matter
field. The corresponding spin network amplitudes are given as multiple
integrals of propagators which are matrix spherical functions.Comment: 30 pages, 9 figures, further remarks and references added. Version to
appear in Class. Quant. Gra
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