26,341 research outputs found
Saturn S-IB stage Final static test report, stage S-IB-2
Acceptance test firing of Saturn flight stage S-IB-
Saturn S-IB stage Final static test report, stage S-IB-4
Acceptance static test firing data for Saturn flight stage S-IB-
Cohomology of toric line bundles via simplicial Alexander duality
We give a rigorous mathematical proof for the validity of the toric sheaf
cohomology algorithm conjectured in the recent paper by R. Blumenhagen, B.
Jurke, T. Rahn, and H. Roschy (arXiv:1003.5217). We actually prove not only the
original algorithm but also a speed-up version of it. Our proof is independent
from (in fact appeared earlier on the arXiv than) the proof by H. Roschy and T.
Rahn (arXiv:1006.2392), and has several advantages such as being shorter and
cleaner and can also settle the additional conjecture on "Serre duality for
Betti numbers" which was raised but unresolved in arXiv:1006.2392.Comment: 9 pages. Theorem 1.1 and Corollary 1.2 improved; Abstract and
Introduction modified; References updated. To appear in Journal of
Mathematical Physic
Distribution of chirality in the quantum walk: Markov process and entanglement
The asymptotic behavior of the quantum walk on the line is investigated
focusing on the probability distribution of chirality independently of
position. The long-time limit of this distribution is shown to exist and to
depend on the initial conditions, and it also determines the asymptotic value
of the entanglement between the coin and the position. It is shown that for
given asymptotic values of both the entanglement and the chirality distribution
it is possible to find the corresponding initial conditions within a particular
class of spatially extended Gaussian distributions. Moreover it is shown that
the entanglement also measures the degree of Markovian randomness of the
distribution of chirality.Comment: 5 pages, 3 figures, It was accepted in Physcial Review
Cohomology of Line Bundles: Applications
Massless modes of both heterotic and Type II string compactifications on
compact manifolds are determined by vector bundle valued cohomology classes.
Various applications of our recent algorithm for the computation of line bundle
valued cohomology classes over toric varieties are presented. For the heterotic
string, the prime examples are so-called monad constructions on Calabi-Yau
manifolds. In the context of Type II orientifolds, one often needs to compute
equivariant cohomology for line bundles, necessitating us to generalize our
algorithm to this case. Moreover, we exemplify that the different terms in
Batyrev's formula and its generalizations can be given a one-to-one
cohomological interpretation.
This paper is considered the third in the row of arXiv:1003.5217 and
arXiv:1006.2392.Comment: 56 pages, 8 tables, cohomCalg incl. Koszul extension available at
http://wwwth.mppmu.mpg.de/members/blumenha/cohomcalg
Picard group of hypersurfaces in toric 3-folds
We show that the usual sufficient criterion for a generic hypersurface in a
smooth projective manifold to have the same Picard number as the ambient
variety can be generalized to hypersurfaces in complete simplicial toric
varieties. This sufficient condition is always satisfied by generic K3 surfaces
embedded in Fano toric 3-folds.Comment: 14 pages. v2: some typos corrected. v3: Slightly changed title. Final
version to appear in Int. J. Math., incorporates many (mainly expository)
changes suggested by the refere
Continuous families of isospectral Heisenberg spin systems and the limits of inference from measurements
We investigate classes of quantum Heisenberg spin systems which have
different coupling constants but the same energy spectrum and hence the same
thermodynamical properties. To this end we define various types of
isospectrality and establish conditions for their occurence. The triangle and
the tetrahedron whose vertices are occupied by spins 1/2 are investigated in
some detail. The problem is also of practical interest since isospectrality
presents an obstacle to the experimental determination of the coupling
constants of small interacting spin systems such as magnetic molecules
On the integral cohomology of smooth toric varieties
Let be a smooth, not necessarily compact toric variety. We show
that a certain complex, defined in terms of the fan , computes the
integral cohomology of , including the module structure over the
homology of the torus. In some cases we can also give the product. As a
corollary we obtain that the cycle map from Chow groups to integral Borel-Moore
homology is split injective for smooth toric varieties. Another result is that
the differential algebra of singular cochains on the Borel construction of
is formal.Comment: 10 page
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