3,369 research outputs found
Preliminary Results on Contents of Resveratrol in Wine of Organic and Conventional Vineyards
Phytoalexins are compounds synthesised by plants in response to various stresses. In grapevines, these compounds belong to the stilbene family. Several studies have shown that resveratrol is usually triggered by infection of berries by Botrytis cinerea. In organic viticulture, grapevines are usually more stressed by attempted or successful infections of various pathogens than in conventionally grown grapevines. Furthermore, crop protection agents such as acidified clays or copper may trigger defence reactions of the plants. The aim of this study was to verify if differences between organically and conventionally produced wines exist. The preliminary results will be used as a starting point for further research of quality aspects of organic grape-vine production
Narrow-escape times for diffusion in microdomains with a particle-surface affinity: Mean-field results
We analyze the mean time t_{app} that a randomly moving particle spends in a
bounded domain (sphere) before it escapes through a small window in the
domain's boundary. A particle is assumed to diffuse freely in the bulk until it
approaches the surface of the domain where it becomes weakly adsorbed, and then
wanders diffusively along the boundary for a random time until it desorbs back
to the bulk, and etc. Using a mean-field approximation, we define t_{app}
analytically as a function of the bulk and surface diffusion coefficients, the
mean time it spends in the bulk between two consecutive arrivals to the surface
and the mean time it wanders on the surface within a single round of the
surface diffusion.Comment: 8 pages, 1 figure, submitted to JC
Lamplighter model of a random copolymer adsorption on a line
We present a model of an AB-diblock random copolymer sequential
self-packaging with local quenched interactions on a one-dimensional infinite
sticky substrate. It is assumed that the A-A and B-B contacts are favorable,
while A-B are not. The position of a newly added monomer is selected in view of
the local contact energy minimization. The model demonstrates a
self-organization behavior with the nontrivial dependence of the total energy,
(the number of unfavorable contacts), on the number of chain monomers, :
for quenched random equally probable distribution of A- and
B-monomers along the chain. The model is treated by mapping it onto the
"lamplighter" random walk and the diffusion-controlled chemical reaction of
type with the subdiffusive motion of reagents.Comment: 8 pages, 5 figure
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