1,257 research outputs found
Evaluation and registration of plant protection inputs for organic farming
Organic farmers may only use those plant protection products which are listed in Annex II B of the ‘Organic Regulation’ 2092/91 and also registered for use at national level. At present, new compounds may only be listed in Reg. 2092/91, if they do not come into direct contact with the crop (although in perennial crops, contact outside the growing season of the edible parts is possible), which is a major obstacle for progress. The EU-funded ORGANIC INPUTS EVALUATION project aims at making Reg. 2092/91 more flexible with regard to new products, while safeguarding the principles of organic farming. Registra-tion under the ‘Pesticide Directive’ 91/414 represents a considerable financial hurdle. The REBECA project will propose registration requirements which are better adapted for biological control agents, plant extracts and other low-risk products. The aim is to accelerate registration and make it more cost-effective, without compromises to the level of safety
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
New alphabet-dependent morphological transition in a random RNA alignment
We study the fraction of nucleotides involved in the formation of a
cactus--like secondary structure of random heteropolymer RNA--like molecules.
In the low--temperature limit we study this fraction as a function of the
number of different nucleotide species. We show, that with changing ,
the secondary structures of random RNAs undergo a morphological transition:
for as the chain length goes to infinity,
signaling the formation of a virtually "perfect" gapless secondary structure;
while , what means that a non-perfect structure with
gaps is formed. The strict upper and lower bounds are
proven, and the numerical evidence for is presented. The relevance
of the transition from the evolutional point of view is discussed.Comment: 4 pages, 3 figures (title is changed, text is essentially reworked),
accepted in PR
Progressive retinal degeneration and glial activation in the Cln6nclf mouse model of neuronal ceroid lipofuscinosis : a beneficial effect of DHA and Curcumin supplementation
Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative lysosomal storage disorders characterized by vision loss, mental and motor deficits, and spontaneous seizures. Neuropathological analyses of autopsy material from NCL patients and animal models revealed brain atrophy closely associated with glial activity. Earlier reports also noticed loss of retinal cells and reactive gliosis in some forms of NCL. To study this phenomenon in detail, we analyzed the ocular phenotype of CLN6nclf mice, an established mouse model for variant-late infantile NCL. Retinal morphometry, immunohistochemistry, optokinetic tracking, electroretinography, and mRNA expression were used to characterize retinal morphology and function as well as the responses of Müller cells and microglia. Our histological data showed a severe and progressive degeneration in the CLN6nclf retina co-inciding with reactive Müller glia. Furthermore, a prominent phenotypic transformation of ramified microglia to phagocytic, bloated, and mislocalized microglial cells was identified in CLN6nclf retinas. These events overlapped with a rapid loss of visual perception and retinal function. Based on the strong microglia reactivity we hypothesized that dietary supplementation with immuno-regulatory compounds, curcumin and docosahexaenoic acid (DHA), could ameliorate microgliosis and reduce retinal degeneration. Our analyses showed that treatment of three-week-old CLN6nclf mice with either 5% DHA or 0.6% curcumin for 30 weeks resulted in a reduced number of amoeboid reactive microglia and partially improved retinal function. DHA-treatment also improved the morphology of CLN6nclf retinas with a preserved thickness of the photoreceptor layer in most regions of the retina. Our results suggest that microglial reactivity closely accompanies disease progression in the CLN6nclf retina and both processes can be attenuated with dietary supplemented immuno-modulating compounds
Vacuum Cherenkov radiation
Within the classical Maxwell-Chern-Simons limit of the Standard-Model
Extension (SME), the emission of light by uniformly moving charges is studied
confirming the possibility of a Cherenkov-type effect. In this context, the
exact radiation rate for charged magnetic point dipoles is determined and found
in agreement with a phase-space estimate under certain assumptions.Comment: 4 pages, REVTeX
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