5,720 research outputs found
Almost closed 1-forms
We construct an algebraic almost closed 1-form with zero scheme not
expressible (even locally) as the critical locus of a holomorphic function on a
nonsingular variety. The result answers a question of Behrend-Fantechi. We
correct here an error in our paper [MPT] where an incorrect construction with
the same claimed properties was proposed.Comment: 16 page
Large-time Behavior of Solutions to the Inflow Problem of Full Compressible Navier-Stokes Equations
Large-time behavior of solutions to the inflow problem of full compressible
Navier-Stokes equations is investigated on the half line .
The wave structure which contains four waves: the transonic(or degenerate)
boundary layer solution, 1-rarefaction wave, viscous 2-contact wave and
3-rarefaction wave to the inflow problem is described and the asymptotic
stability of the superposition of the above four wave patterns to the inflow
problem of full compressible Navier-Stokes equations is proven under some
smallness conditions. The proof is given by the elementary energy analysis
based on the underlying wave structure. The main points in the proof are the
degeneracies of the transonic boundary layer solution and the wave interactions
in the superposition wave.Comment: 27 page
A Millimeter-Wave Achromatic Half Wave Plate
We have constructed an achromatic half wave plate (AHWP) suitable for the
millimeter wavelength band. The AHWP was made from a stack of three sapphire
a-cut birefringent plates with the optical axes of the middle plate rotated by
50.5 degrees with respect to the aligned axes of the other plates. The measured
modulation efficiency of the AHWP at 110 GHz was %. In contrast,
the modulation efficiency of a single sapphire plate of the same thickness was
%. Both results are in close agreement with theoretical predictions.
The modulation efficiency of the AHWP was constant as a function of incidence
angles between 0 and 15 degrees. We discuss design parameters of an AHWP in the
context of astrophysical broad band polarimetry at the millimeter wavelength
band.Comment: In print - Applied Optics, 14 pages, 7 figure
Kodaira-Spencer formality of products of complex manifolds
We shall say that a complex manifold is emph{Kodaira-Spencer formal} if its Kodaira-Spencer differential graded Lie algebra
is formal; if this happen, then the deformation theory of
is completely determined by the graded Lie algebra and the base space of the semiuniversal deformation is a quadratic singularity..
Determine when a complex manifold is Kodaira-Spencer formal is generally difficult and
we actually know only a limited class of cases where this happen. Among such examples we have
Riemann surfaces, projective spaces, holomorphic Poisson manifolds with surjective anchor map
and every compact K"{a}hler manifold with trivial or torsion canonical
bundle.
In this short note we investigate the behavior of this property under finite products. Let be compact complex manifolds; we prove that whenever and are
K"{a}hler, then is Kodaira-Spencer formal if and only if the same
holds for and . A revisit of a classical example by Douady shows that the above result fails if the K"{a}hler assumption is droppe
Deformation of Schild String
We attempt to construct new superstring actions with a -plet of Majorana
fermions , where is the dimensional space-time
index and is the two dimensional spinor index, by deforming the Schild
action. As a result, we propose three kinds of actions: the first is invariant
under N=1 (the world-sheet) supersymmetry transformation and the
area-preserving diffeomorphism. The second contains the Yukawa type
interaction. The last possesses some non-locality because of bilinear terms of
. The reasons why completing a Schild type superstring action
with is difficult are finally discussed.Comment: 12 pages, Latex, both title and abstract are changed, discussion of
some relations among our results, Nambu-Goto string and super Yang-Mills
theories, added. Results unchange
Magnetic order in the quasi-two-dimensional easy-plane XXZ model
A Green's-function theory of antiferromagnetic short-range and long-range
order (LRO) in the quasi-two-dimensional easy-plane XXZ model is
presented. As the main new result, {\it two} phase transitions due to the
combined influence of spatial and spin anisotropy are found, where below the
higher and lower N\'{e}el temperature there occurs LRO in the transverse and in
both the transverse and longitudinal spin correlators, respectively. Comparing
the theory with neutron-scattering data for the correlation length of , a very good agreement in the whole temperature dependence is
obtained. Moreover, for , , and the second phase with longitudinal LRO is predicted to
appear far below room temperature.Comment: 7 pages, 5 figure
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