3,762 research outputs found
Binomial Difference Ideal and Toric Difference Variety
In this paper, the concepts of binomial difference ideals and toric
difference varieties are defined and their properties are proved. Two canonical
representations for Laurent binomial difference ideals are given using the
reduced Groebner basis of Z[x]-lattices and regular and coherent difference
ascending chains, respectively. Criteria for a Laurent binomial difference
ideal to be reflexive, prime, well-mixed, perfect, and toric are given in terms
of their support lattices which are Z[x]-lattices. The reflexive, well-mixed,
and perfect closures of a Laurent binomial difference ideal are shown to be
binomial. Four equivalent definitions for toric difference varieties are
presented. Finally, algorithms are given to check whether a given Laurent
binomial difference ideal I is reflexive, prime, well-mixed, perfect, or toric,
and in the negative case, to compute the reflexive, well-mixed, and perfect
closures of I. An algorithm is given to decompose a finitely generated perfect
binomial difference ideal as the intersection of reflexive prime binomial
difference ideals.Comment: 72 page
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Gene duplication and an accelerated evolutionary rate in 11S globulin genes are associated with higher protein synthesis in dicots as compared to monocots
Background: Seed storage proteins are a major source of dietary protein, and the
content of such proteins determines both the quantity and quality of crop yield.
Significantly, examination of the protein content in the seeds of crop plants shows a
distinct difference between monocots and dicots. Thus, it is expected that there are
different evolutionary patterns in the genes underlying protein synthesis in the seeds
of these two groups of plants.
Results: Gene duplication, evolutionary rate and positive selection of a major gene
family of seed storage proteins (the 11S globulin genes), were compared in dicots and
monocots. The results, obtained from five species in each group, show more gene
duplications, a higher evolutionary rate and positive selections of this gene family in
dicots, which are rich in 11S globulins, but not in the monocots.
Conclusion: Our findings provide evidence to support the suggestion that gene
duplication and an accelerated evolutionary rate may be associated with higher protein
synthesis in dicots as compared to monocots
Hydrogen production by mixed culture of several facultative bacteria and anaerobic bacteria
AbstractThe characteristic of hydrogen production by facultative anaerobic bacteria, obligate anaerobic bacteria and their mixed culture was studied by the batch culture method. The results showed that, due to the synergistic effect between facultative bacteria and anaerobic bacteria, the ability of hydrogen production in the mixed culture was much better than that in the pure culture. Especially, the culture Scheme No.7 mixed up with three strains (Bacterium. E: Bacterium. B: Bacterium. P = 1:1:1) not only had the best hydrogen production capacity (1.885 mol H2/mol glucose) and maximum average hydrogen production rate (212.2 mL/(L·h)), but also had stable hydrogen production under continuous culture conditions, which was 1.968 mol H2/mol glucose
meson effects on neutron stars in the modified quark-meson coupling model
The properties of neutron stars are investigated by including meson
field in the Lagrangian density of modified quark-meson coupling model. The
population with meson is larger than that without
meson at the beginning, but it becomes smaller than that without meson
as the appearance of . The meson has opposite effects on
hadronic matter with or without hyperons: it softens the EOSes of hadronic
matter with hyperons, while it stiffens the EOSes of pure nucleonic matter.
Furthermore, the leptons and the hyperons have the similar influence on
meson effects. The meson increases the maximum masses of
neutron stars. The influence of on the meson effects
are also investigated.Comment: 10 pages, 6 figures, 4 table
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