3,331 research outputs found
Cohen-Macaulayness of monomial ideals and symbolic powers of Stanley-Reisner ideals
We present criteria for the Cohen-Macaulayness of a monomial ideal in terms
of its primary decomposition. These criteria allow us to use tools of graph
theory and of linear programming to study the Cohen-Macaulayness of monomial
ideals which are intersections of prime ideal powers. We can characterize the
Cohen-Macaulayness of the second symbolic power or of all symbolic powers of a
Stanley-Reisner ideal in terms of the simplicial complex. These
characterizations show that the simplicial complex must be very compact if some
symbolic power is Cohen-Macaulay. In particular, all symbolic powers are
Cohen-Macaulay if and only if the simplicial complex is a matroid complex. We
also prove that the Cohen-Macaulayness can pass from a symbolic power to
another symbolic powers in different ways.Comment: The published version of this paper contains a gap in the proofs of
Theorem 2.5 and Theorem 3.5. This version corrects the proofs with almost the
same arguments. Moreover, we have to modify the definition of tight complexes
in Theorem 2.5. These changes don't affect other things in the published
version. A corrigendum has been sent to the journa
The Current Adoption of Dry-Direct Seeding Rice (DDSR) in Thailand and Lessons Learned for Mekong River Delta of Vietnam
The paper documents the joint study trip, organized by CCAFS Southeast Asia for Vietnamese rice researchers, extension workers, as well as local decision makers, to visit Thailand in April 2018. The goal of the study trip was to observe and learn the experience of Thai farmers on the large-scale adoption process of dry-direct seeding rice (DDSR), a viable alternative to address regional scarcity of fresh water in irrigation caused by the drought and salinity intrusion in the Mekong River Delta
Folding model study of the elastic scattering at low energies
The folding model analysis of the elastic scattering at the
incident energies below the reaction threshold of 34.7 MeV (in the lab system)
has been done using the well-tested density dependent versions of the M3Y
interaction and realistic choices for the He density. Because the
absorption is negligible at the energies below the reaction threshold, we were
able to probe the optical potential at low energies quite
unambiguously and found that the overlap density used to
construct the density dependence of the M3Y interaction is strongly distorted
by the Pauli blocking. This result gives possible explanation of a
long-standing inconsistency of the double-folding model in its study of the
elastic and -nucleus scattering at low energies using
the same realistic density dependent M3Y interaction
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