2,720 research outputs found
Infinitesimal cohomology and the Chern character to negative cyclic homology
There is a Chern character from K-theory to negative cyclic homology. We show
that it preserves the decomposition coming from Adams operations, at least in
characteristic 0. This is done by using infinitesimal cohomology to reduce to
the case of a nilpotent ideal (which had been established by Cathelineau some
time ago).Comment: Included reference for identification of relative Chern and rational
homotopy theory characters; some minor editing for clarit
A negative answer to a question of Bass
In this companion paper to arXiv:0802.1928 we provide an example of an
isolated surface singularity over a number field such that but . This answers, negatively, a
question of Bass.Comment: The paper was previously part of arXiv:0802.192
Potential and Limits of Pesticide Free Apple Growing by a Self-Regulating Orchard Set-Up: Project Presentation and First Experiences
Different research groups have already proven that flowering plants in orchards can enhance beneficial arthropods. Even within the tree rows different beneficial can be supported by selected plant species. In most experimental work done to stabilize the apple production system only single interaction effects were tested. However until now, no research group has quantified the additive effects of multiple measures on systembiodiversity and on the production economy.
Our experiment combines all known measures of indirect pest and disease control measures in a near-to practical production model orchard without the use of any pesticide (not even organic ones). The orchard is split in 4 blocks: in two of them bio-control measures e.g. application of Granulosis Virus against codling moth (C. Pomonella) are applied; in the other two blocks no bio-control is applied. Standard commercial organic and integrated orchards with the disease-susceptible cultivar Gala in the vicinity of the model orchard are assessed by the same methods and serve as reference.
Our intermediate results reveal that the self-regulating orchard developed already in the 2nd and 3rd leaf a clearly higher flora and fauna biodiversity compared to the reference orchards. The same happened in relation to the specific fruit beneficial e.g. the populations of aphid predators. In the self-regulating orchard they were capable to keep the aphid damages – in particular of the powdery apple aphid (D. plantaginea) - on trees and fruits under a commercially relevant level although the initial abundance of aphid colonies in spring was by far over the common threshold value. It is planned to continue the experiment until 2016
The Yoneda algebra of a graded Ore extension
Let A be a connected-graded algebra with trivial module k, and let B be a
graded Ore extension of A. We relate the structure of the Yoneda algebra E(A)
:= Ext_A(k,k) to E(B). Cassidy and Shelton have shown that when A satisfies
their K_2 property, B will also be K_2. We prove the converse of this result.Comment: 9 page
A note on compactly generated co-t-structures
The idea of a co-t-structure is almost "dual" to that of a t-structure, but
with some important differences. This note establishes co-t-structure analogues
of Beligiannis and Reiten's corresponding results on compactly generated
t-structures.Comment: 10 pages; details added to proofs, small correction in the main
resul
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