51,199 research outputs found
Isotrivial VMRT-structures of complete intersection type
The family of varieties of minimal rational tangents on a quasi-homogeneous
projective manifold is isotrivial. Conversely, are projective manifolds with
isotrivial varieties of minimal rational tangents quasi-homogenous? We will
show that this is not true in general, even when the projective manifold has
Picard number 1. In fact, an isotrivial family of varieties of minimal rational
tangents needs not be locally flat in differential geometric sense. This leads
to the question for which projective variety Z, the Z-isotriviality of
varieties of minimal rational tangents implies local flatness. Our main result
verifies this for many cases of Z among complete intersections.Comment: Some errors in Section 8 and Lemma 8.1 corrected. To appear in The
Asian Journal of Mathematics (AJM) special issue dedicated to Ngaiming Mok's
60th birthda
Comment on "Geometric phases for mixed states during cyclic evolutions"
It is shown that a recently suggested concept of mixed state geometric phase
in cyclic evolutions [2004 {\it J. Phys. A} {\bf 37} 3699] is gauge dependent.Comment: Comment to the paper L.-B. Fu and J.-L. Chen, J. Phys. A 37, 3699
(2004); small changes; journal reference adde
SEASAT views oceans and sea ice with synthetic aperture radar
Fifty-one SEASAT synthetic aperture radar (SAR) images of the oceans and sea ice are presented. Surface and internal waves, the Gulf Stream system and its rings and eddies, the eastern North Pacific, coastal phenomena, bathymetric features, atmospheric phenomena, and ship wakes are represented. Images of arctic pack and shore-fast ice are presented. The characteristics of the SEASAT SAR system and its image are described. Maps showing the area covered, and tables of key orbital information, and listing digitally processed images are provided
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