127,402 research outputs found
On the minimal number of critical points of functions on h-cobordisms
Let (W,M,M'), dim W > 5, be a non-trivial h-cobordism (i.e., the Whitehead
torsion of (W,V) is non-zero). We prove that every smooth function f: W -->
[0,1], f(M)=0, f(M')=1 has at least 2 critical points. This estimate is sharp:
W possesses a function as above with precisely two critical points.Comment: 7 pages, Late
Elliptic operators in odd subspaces
An elliptic theory is constructed for operators acting in subspaces defined
via odd pseudodifferential projections. Subspaces of this type arise as
Calderon subspaces for first order elliptic differential operators on manifolds
with boundary, or as spectral subspaces for self-adjoint elliptic differential
operators of odd order. Index formulas are obtained for operators in odd
subspaces on closed manifolds and for general boundary value problems. We prove
that the eta-invariant of operators of odd order on even-dimesional manifolds
is a dyadic rational number.Comment: 27 page
Charge density wave transport in submicron antidot arrays in NbSe3
We demonstrate for the first time that a periodic array of submicrometer
holes (antidots) can be patterned into thin single NbSe3 crystals. We report on
the study of charge density wave (CDW) transport of the network of mesoscopic
units between antidots. Size of the elementary unit can be as small as 0.5
micron along the chain axis and (0.2 micron) x (0.3 micron) in cross section.
We observe size effects for Ohmic residual resistance and in CDW transport
current-voltage characteristics in submicronic networks.Comment: 4 pages with 1 table and 10 figures. Submitted to European Physical
Journa
Dynamics of meteor streams
The overwhelming majority of meteor streams are generally assumed to be formed due to the decay of comets. The most effective process of the release of solid particles from a cometary nucleus is their ejection by sublimating gases when the comet approaches the Sun. The results of investigation of the Geminids and Quadrantids meteor stream evolution show that under the influence of planetary perturbations, the stream may originally be flat but then thicken depending on the variation range of orbital inclinations. Eventually, due to planetary perturbations, a meteor stream may take such a shape as to cause the start of several active showers at different solar longitudes
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