1,477 research outputs found
JPL field measurements at the Finney County, Kansas, test site, October 1976: Ground-based microwave radiometric measurements
Microwave brightness temperature measurements were made as part of the Joint Soil Moisture Experiment. These measurements are reported with a description of the JPL microwave radiometry van facility. The data will be used with ground truth data from the test site and microwave data from aircraft overflights to investigate the potential of microwave radiometry for soil moisture remote sensing under field conditions
The table mountain 8-mm-wavelength interferometer
The system components, performance, and calibration of two element radio interferometer operating at 8.33 mm wavelength are discussed. The interferometer employs a 5.5 m and a 3 m diameter antenna on an east-west baseline of 60 or 120 m, yielding fringe spacings at transit of 28 or 14 in. respectively. The broad intermediate frequency bandpass of 100 to 350 MHz and the system noise temperature of 500 K provide high sensitivity for the measurement of continuum sources. The interferometer has been used for high resolution studies of the planets and the Sun, and it is currently being adapted to study solar flare emissions at high spatial and time resolution
Microtubule assembly and in vitro development of bovine oocytes with increased intracellular glutathione level prior to vitrification and in vitro fertilization
Although vitrification is a useful technique for preservation of bovine oocytes, the yield of blastocysts derived from the vitrified oocytes is still low. We have recently reported a new type of cryoinjury, multiple aster formation, by which pronuclear migration and development of vitrified–warmed and in vitro-fertilized bovine oocytes are impaired. The aim of the present study was to investigate the effect of glutathione (GSH) content of vitrified bovine oocytes on multiple aster formation and subsequent in vitro development. Treatment of bovine cumulus–oocyte complexes with β-mercaptoethanol (βME) and l-cysteine (Cys) during in vitro maturation resulted in 2.5-fold higher GSH content not only in fresh control but also in vitrified–warmed oocytes. The percentage of normally fertilized zygotes exhibiting sperm aster(s) was >95% in all four groups (with or without βME/Cys × fresh control or vitrified). The frequency of multiple aster formation in vitrified oocytes (three-fold higher than that in fresh control oocytes) was not affected by the increased level of intracellular GSH with βME/Cys. Consequently, the migration and development of pronuclei as well as the yield of blastocysts from vitrified–warmed oocytes (17 versus 41%) were not improved. In addition, there was no effect of increased GSH level on the yield of blastocysts in fresh control groups.ArticleZYGOTE. 22(4):476-482 (2014)journal articl
Jacobson generators of the quantum superalgebra and Fock representations
As an alternative to Chevalley generators, we introduce Jacobson generators
for the quantum superalgebra . The expressions of all
Cartan-Weyl elements of in terms of these Jacobson generators
become very simple. We determine and prove certain triple relations between the
Jacobson generators, necessary for a complete set of supercommutation relations
between the Cartan-Weyl elements. Fock representations are defined, and a
substantial part of this paper is devoted to the computation of the action of
Jacobson generators on basis vectors of these Fock spaces. It is also
determined when these Fock representations are unitary. Finally, Dyson and
Holstein-Primakoff realizations are given, not only for the Jacobson
generators, but for all Cartan-Weyl elements of .Comment: 27 pages, LaTeX; to be published in J. Math. Phy
Avalanche Dynamics in Wet Granular Materials
We have studied the dynamics of avalanching wet granular media in a rotating
drum apparatus. Quantitative measurements of the flow velocity and the granular
flux during avalanches allow us to characterize novel avalanche types unique to
wet media. We also explore the details of viscoplastic flow (observed at the
highest liquid contents) in which there are lasting contacts during flow,
leading to coherence across the entire sample. This coherence leads to a
velocity independent flow depth at high rotation rates and novel robust pattern
formation in the granular surface.Comment: 5 pages, 3 figures in color, REVTeX4, for smaller pdfs see
http://angel.elte.hu/~tegzes/condmat.htm
Extremal projectors for contragredient Lie (super)symmetries (short review)
A brief review of the extremal projectors for contragredient Lie
(super)symmetries (finite-dimensional simple Lie algebras, basic classical Lie
superalgebras, infinite-dimensional affine Kac-Moody algebras and
superalgebras, as well as their quantum -analogs) is given. Some
bibliographic comments on the applications of extremal projectors are
presented.Comment: 21 pages, LaTeX; typos corrected, references adde
Finite-dimensional representations of the quantum superalgebra and related q-identities
Explicit expressions for the generators of the quantum superalgebra
acting on a class of irreducible representations are given. The
class under consideration consists of all essentially typical representations:
for these a Gel'fand-Zetlin basis is known. The verification of the quantum
superalgebra relations to be satisfied is shown to reduce to a set of
-number identities.Comment: 12 page
Structure of the string R-matrix
By requiring invariance directly under the Yangian symmetry, we rederive
Beisert's quantum R-matrix, in a form that carries explicit dependence on the
representation labels, the braiding factors, and the spectral parameters u_i.
In this way, we demonstrate that there exist a rewriting of its entries, such
that the dependence on the spectral parameters is purely of difference form.
Namely, the latter enter only in the combination u_1-u_2, as indicated by the
shift automorphism of the Yangian. When recasted in this fashion, the entries
exhibit a cleaner structure, which allows to spot new interesting relations
among them. This permits to package them into a practical tensorial expression,
where the non-diagonal entries are taken care by explicit combinations of
symmetry algebra generators.Comment: 9 pages, LaTeX; typos correcte
Quantum superalgebras at roots of unity and non-abelian symmetries of integrable models
We consider integrable vertex models whose Boltzmann weights (R-matrices) are
trigonometric solutions to the graded Yang-Baxter equation. As is well known
the latter can be generically constructed from quantum affine superalgebras
. These algebras do not form a symmetry algebra of the model for
generic values of the deformation parameter when periodic boundary
conditions are imposed. If is evaluated at a root of unity we demonstrate
that in certain commensurate sectors one can construct non-abelian subalgebras
which are translation invariant and supercommute with the transfer matrix and
therefore with all charges of the model. In the line of argument we introduce
the restricted quantum superalgebra and investigate its
root of unity limit. We prove several new formulas involving supercommutators
of arbitrary powers of the Chevalley-Serre generators and derive higher order
quantum Serre relations as well as an analogue of Lustzig's quantum Frobenius
theorem for superalgebras.Comment: 31 pages, tcilatex (minor typos corrected
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