3,349 research outputs found
QCD modeling of hadron physics
We review recent developments in the understanding of meson properties as
solutions of the Bethe-Salpeter equation in rainbow-ladder truncation. Included
are recent results for the pseudoscalar and vector meson masses and leptonic
decay constants, ranging from pions up to c\bar{c} bound states; extrapolation
to b\bar{b} states is explored. We also present a new and improved calculation
of F_\pi(Q^2) and an analysis of the \pi\gamma\gamma transition form factor for
both \pi(140) and \pi(1330). Lattice-QCD results for propagators and the
quark-gluon vertex are analyzed, and the effects of quark-gluon vertex dressing
and the three-gluon coupling upon meson masses are considered.Comment: 17 pages, 19 postscript figures, contribution to the proceedings of
LC05, Cairns, Australia, July 200
Synthesis of novel urethanes from a castor oil derived C22-acyloin
The synthesis of new bio-based chemical building blocks, resulting from the condensation of a renewable C-22 acyloin derived from non-edible castor oil, with mono- and bifunctional isocyanates is reported. The condensation with aliphatic mono-isocyanates was relatively straightforward, however phenyl isocyanates only resulted in low yields together with the formation of a cyclic hemi-aminal during purification. The condensation with diisocyanates was successful for the aliphatic hexamethylene diisocyanate. As for the aromatic 2,4-toluene diisocyanate, a low yield of the desired product was obtained, since a similar ring closing reaction took place. The urethanes were synthesized in order to evaluate their plasticizing and viscosity-modifying properties
Dynamic Decomposition of Spatiotemporal Neural Signals
Neural signals are characterized by rich temporal and spatiotemporal dynamics
that reflect the organization of cortical networks. Theoretical research has
shown how neural networks can operate at different dynamic ranges that
correspond to specific types of information processing. Here we present a data
analysis framework that uses a linearized model of these dynamic states in
order to decompose the measured neural signal into a series of components that
capture both rhythmic and non-rhythmic neural activity. The method is based on
stochastic differential equations and Gaussian process regression. Through
computer simulations and analysis of magnetoencephalographic data, we
demonstrate the efficacy of the method in identifying meaningful modulations of
oscillatory signals corrupted by structured temporal and spatiotemporal noise.
These results suggest that the method is particularly suitable for the analysis
and interpretation of complex temporal and spatiotemporal neural signals
Tomato marchitez virus, a new plant picorna-like virus from tomato related to tomato torrado virus
A new virus was isolated from a tomato plant from the state of Sinaloa in Mexico. This plant showed symptoms locally known as `marchitez diseaseÂż: severe leaf necrosis, beginning at the base of the leaflets, and necrotic rings on the fruits. A virus was isolated from the infected plant consisting of isometric particles with a diameter of approximately 28Âżnm. The viral genome consists of two (+)ssRNA molecules of 7221 (RNA1) and 4898Âżnts (RNA2). The viral capsid contains three coat proteins of 35, 26 and 24ÂżkDa, respectively. The abovementioned characteristics: symptoms, morphology, number and size of coat proteins, and number of RNAs are similar to those of the previously described tomato torrado virus (ToTV). Sequence analysis of the entire viral genome shows that this new virus is related to, but distinct from, ToTV and that these members of two obviously new virus species belong to the recently proposed plant virus genus Torradovirus. For this new virus, the name tomato marchitez virus (ToMarV) is proposed
Anal canal duplication in an 11-year-old-child
Anal canal duplication (ACD) is the least frequent digestive duplication. Symptoms are often absent but tend to increase with age. Recognition is, however, important as almost half of the patients with ACD have concomitant malformations. We present the clinical history of an eleven-year-old girl with ACD followed by a review of symptoms, diagnosis, treatment, and prognosis based on all the reported cases in English literature
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