97 research outputs found
On projective curves of maximal regularity
Let C ⊆ Pr K be a non-degenerate projective curve of degree d > r + 1 of maximal regularity so that C has an extremal secant line L. We show that C ∪ L is arithmetically Cohen Macaulay if d < 2r − 1 and we study the Betti numbers and the Hartshorne-Rao module of the curve C
Tensor product of dualizing complexes over a field
Let be a field, and let be two locally noetherian -schemes
(respectively -formal schemes) with dualizing complexes and
respectively. We show that (respectively its derived
completion) is a dualizing complex over if and only if
is locally noetherian of finite Krull dimension.Comment: 13 pages, final version, to appear in the Journal of Commutative
Algebr
Coarsening of graded local cohomology
Some criteria for graded local cohomology to commute with coarsening functors
are proven, and an example is given where graded local cohomology does not
commute with coarsening.Comment: minor correction
Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution
Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings
On varieties of almost minimal degree II: A rank-depth formula
Let denote a variety of almost minimal degree other than a normal del Pezzo variety. Then is the projection of a rational normal scroll from a point We show that the arithmetic depth of can be expressed in terms of the rank of the matrix where is the matrix of linear forms whose minors define the secant variety of $ \tilde X.
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