4,970 research outputs found
Biological activity of glucosinolate derived compounds isolated from seed meal of Brassica crops and evaluated as plant and food protection agents
Glucosinolates are amino acid derived allelochemicals characteristic of plants of the order Capparales. These compounds are present in seeds of agriculturally common Brassica crops in varying quantities depending on the species (ref). The use of the remaining seed cake after oil extraction has traditionally been limited by the concentration of these compounds. However, the extraction of glucosinolates from seed meal is nowadays possible and it further contributes to an increased quality of the seed meal for feed (Sørensen et al., this conference). Glucosinolates are hydrolysed by endogenous enzymes (myrosinases; EC 3.2.1.147) and a number of compounds are produced depending on the parent glucosinolate and the environmental conditions.1 Among these compounds, oxazolidine-2-thiones are known for their antinutritional effects on monogastric animals, whereas isothiocyanates are fungicidal, nematocidal and herbicidal.2,3 The possibility for using glucosinolates as precursors for environmental friendly biocides therefore exists, which could contribute to increase the value of the Brassica seed meal
FliPpr: A Prettier Invertible Printing System
When implementing a programming language, we often write
a parser and a pretty-printer. However, manually writing both programs
is not only tedious but also error-prone; it may happen that a pretty-printed
result is not correctly parsed. In this paper, we propose FliPpr,
which is a program transformation system that uses program inversion
to produce a CFG parser from a pretty-printer. This novel approach
has the advantages of fine-grained control over pretty-printing, and easy
reuse of existing efficient pretty-printer and parser implementations
Doped coupled frustrated spin-1/2 chains with four-spin exchange
The role of various magnetic inter-chain couplings is investigated by
numerical methods in doped frustrated quantum spin chains. A non-magnetic
dopant introduced in a gapped spin chain releases a free spin-1/2 soliton. The
formation of a local magnetic moment is analyzed in term of soliton
confinement. A four-spin coupling which might originate from cyclic exchange is
shown to produce such a confinement in contrast to transverse magnetic
exchange. Dopants on different chains experience an effective space-extended
non-frustrating pairwise spin interaction.Comment: Few modifications and references added. Submitted to PR
The Ground State Energy of Heavy Atoms According to Brown and Ravenhall: Absence of Relativistic Effects in Leading Order
It is shown that the ground state energy of heavy atoms is, to leading order,
given by the non-relativistic Thomas-Fermi energy. The proof is based on the
relativistic Hamiltonian of Brown and Ravenhall which is derived from quantum
electrodynamics yielding energy levels correctly up to order Ry
Exact Results for the Bipartite Entanglement Entropy of the AKLT spin-1 chain
We study the entanglement between two domains of a spin-1 AKLT chain subject
to open boundary conditions. In this case the ground-state manifold is
four-fold degenerate. We summarize known results and present additional exact
analytical results for the von Neumann entanglement entropy, as a function of
both the size of the domains and the total system size for {\it all} four
degenerate ground-states. In the large limit the entanglement entropy
approaches and for the and states,
respectively. In all cases, it is found that this constant is approached
exponentially fast defining a length scale equal to the known
bulk correlation length.Comment: 11 pages, 3 figure
Reply to the "Comment on 'Phase diagram of an impurity in the spin-1/2 chain: two channel Kondo effect versus Curie law'"
In a comment by A.A. Zvyagin the phase diagram in our Letter [Phys. Rev.
Lett. 86, 516 (2001)] was critisized of being incomplete and a new fixed point
was suggested. We show that this point is in fact not a fixed point and that
the phase diagram is correct as presented.Comment: Reply to a comment by A.A. Zvyagin. 1 page, 1 figure. The latest
version in PDF format is available from
http://fy.chalmers.se/~eggert/papers/reply.pd
Random Fixed Point of Three-Dimensional Random-Bond Ising Models
The fixed-point structure of three-dimensional bond-disordered Ising models
is investigated using the numerical domain-wall renormalization-group method.
It is found that, in the +/-J Ising model, there exists a non-trivial fixed
point along the phase boundary between the paramagnetic and ferromagnetic
phases. The fixed-point Hamiltonian of the +/-J model numerically coincides
with that of the unfrustrated random Ising models, strongly suggesting that
both belong to the same universality class. Another fixed point corresponding
to the multicritical point is also found in the +/-J model. Critical properties
associated with the fixed point are qualitatively consistent with theoretical
predictions.Comment: 4 pages, 5 figures, to be published in Journal of the Physical
Society of Japa
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